The killing of a mother and daughter would not have happened if two teenagers had not formed an "intense, toxic relationship", a court has heard.

Elizabeth Edwards, 49, and her 13-year-old daughter Katie were found stabbed to death at their home in Spalding, Lincolnshire in April.
A 15-year-old girl has admitted manslaughter but denies murder on the grounds of diminished responsibility.
A 15-year-old boy has already pleaded guilty to murder.
Consultant forensic psychiatrist Dr Philip Joseph told a jury at Nottingham Crown Court the bond between the couple had been the catalyst for the killings.
He told jurors: "If they had not had this intense, toxic relationship this would never have happened. It is the relationship that is behind the killings."
Dr Joseph said that during his interview with the girl in September 2016 she said she had first become aware of her boyfriend in 2013 but they did not begin a relationship until May 2015.
She told the psychiatrist that she and the boy had the "same attitude to life".
She said things had initially gone well between the couple, saying she had "felt happy for once" and it was "the closest I've ever felt to anyone".
Dr Joseph described the girl as being "inappropriately upbeat" and "cheerful" during the two-and-a-half hour interview.
When he asked her how she and the boy had felt after killing the two women she said: "We felt laid back about what we had done and neither of us felt that bad about it."
He said she had described the couple's plans to commit suicide after the killings as "half-hearted" and that "for some reason" it did not happen.
When asked if she thought there was something wrong with her she told him: "Everything is wrong with me. For a 15-year-old girl to be talking about it like it was a breeze means there must be something wrong with me."
Asked about the diagnosis of Dr Indranil Chakrabarti who had earlier told the court that the girl had been suffering from a mental disorder, Dr Joseph said he did not believe the diagnosis was correct.
He went on to say that even if she had been suffering from such a disorder it would not have impaired her ability to understand her conduct or make rational decisions.
"I disagree with the diagnosis and even if she did have some form of adjustment disorder it had no link to the killing," he said.
"She was not suffering from an adjustment disorder nor was she suffering from any other psychiatric condition.
"To suggest that anyone who kills has impaired rational judgement, the law says that is complete nonsense.
"[Somebody with such a disorder] might lash out but it would be an outburst, an uncontrolled act, but I've never heard of a case of a planned killing as a result of an adjustment disorder."
Earlier, psychiatrist Dr Chakrabarti told Nottingham Crown Court the girl had been suffering from a mental disorder at the time of the killings that meant she was incapable of forming rational thoughts.
Under cross-examination from prosecutor Peter Joyce QC, he agreed she had been excited about the killing and said she had felt "relieved" after the murders, but he rejected claims she was "glad" the women were dead.
Dr Chakrabarti admitted there was planning but said the defendant's thinking had been "impaired by the mental disorder".
He said: "I do not think that killing two people is rational thinking in any way."
He added that as a result of the disorder he believed "she did not understand her conduct" at the time of the killings.
He told the jury: "She knew she was going to kill them but what I understand is that she was unable to understand her conduct and what consequences that meant for the victims."
During the assessment the girl had appeared "relieved but not remorseful" as a result of the killings, the court was told.
Prior to his assessment, the girl had not previously been assessed as having any mental illnesses.
The trial continues.


Tottenham MP David Lammy has said he refused to attend a vigil for Mark Duggan because he did not want to share a platform with "anarchist groups".

He told The Andrew Marr Show he did not want to appear with "people that don't accept that a jury laboured and reached a decision".
Up to 500 people gathered at Tottenham Police Station on Saturday.
On Wednesday, an inquest jury concluded Mark Duggan was lawfully killed when he was shot dead by police in August 2011.
Mr Lammy said: "I've done a lot to support this family and I will continue to do that but I will not share a platform with anarchist groups and people that don't accept that a jury laboured and reached a decision."
Jurors concluded that Mark Duggan was in possession of a gun before he was shot, although not holding one when he was killed.
They had to consider whether he posed an imminent threat to police when he was killed.
The Duggan family reacted angrily to the conclusion, saying Mark Duggan had been "executed" and shouting "No justice, no peace".
The gathering on Saturday was used to protest against deaths in police custody, though the Duggan family had called for a peaceful vigil.
It included representatives from unions including the National Union of Teachers and the National Union of Rail, Maritime and Transport Workers.
Stafford Scott who works for rights and race advocacy in Tottenham questioned why Mr Lammy had not attended the vigil in a speech he made on the steps of the police station.
Labour MP Mr Lammy said: "There's a legal process that continues. There's an IPCC [Independent Police Complaints Commission] investigation and it's my job to continue to put pressure on that organisation, but anarchy and extreme protest groups I'm not prepared to share a platform with and I've always been consistent on that."
Addressing the reaction to the jury's conclusion, he said: "The central issue it seems to me is that you have to have a Met that looks like London and we are a long way off that.
"You go to New York and you see a police force that looks like the city and I don't think you can have a global city where less than 10% of the Met come from minority ethnic backgrounds.
"In fact we are in a situation where many of the Met aren't even Londoners, black or white. They are from other parts of the country."
Asked if he supports the idea of police wearing cameras, he said: "Definitely. I think if we had police cameras in this case we would know exactly where the gun was and how it left the car."


More than 27,000 people suspected of illegally entering the UK have been arrested over the past three years, figures obtained by the BBC show.

The statistics from 39 police forces in England, Wales and Northern Ireland showed nearly a 25% rise in arrests from 2013 to 2015.
Many of those arrested were found at motorway service stations and truck stops, having hidden in lorries.
The Home Office said it wanted "long-term solutions" to illegal migration.
Four forces - including Police Scotland - did not provide data, while some only provided partial information.
Commons Home Affairs Committee chairman Keith Vaz called for "urgent action" to tackle the problem, while former Special Branch ports officer Chris Hobbs called the figures "appalling".
BBC home affairs correspondent Danny Shaw said the figures were the most comprehensive yet to be compiled, and highlighted the increasing burden placed on police by migrants who have slipped through border controls.
The figures, released under the Freedom of Information (FOI) Act, show officers made 7,709 arrests for illegal entry in 2013.
The number increased slightly to 7,913 the following year and rose to 9,600 in 2015, when many countries in Europe were struggling to deal with the refugee crisis.
The total over the period from January 2013 to April this year was 27,800.
This does not include people arrested for staying longer in the country than their visa entitled them to, nor those detained at ports and airports, who are dealt with by Border Force staff.
Meanwhile, a separate FOI request showed that across the Channel, officials at ports in France, Belgium and the Netherlands intercepted 145,157 would-be migrants to the UK from 2013 to the end of March 2016.
By BBC home affairs correspondent Danny Shaw
If you want to find figures on legal immigration, the Office for National Statistics has plenty. Illegal immigration is a different matter.
Clandestine migrants don't want to be found, let alone counted for statistical purposes.
Besides, the government wouldn't be keen to advertise how many people are in the country who shouldn't be.
But the police arrest figures provide a good indicator of the scale of the problem.
Of course the numbers don't include illegal entrants who've managed to stay under the radar.
But they do highlight the increasing burden on police presented by those who've slipped through border controls unnoticed.
Metropolitan - 6,834
Thames Valley - 2,107
Kent - 2,092
West Midlands - 1,692
Greater Manchester - 1,538
Surrey - 1,425
Mr Hobbs said: "Obviously these people are still getting through.
"And these are the ones that are being detected by police. What about the ones who are getting through undetected, who simply disappear?"
"The figures really are unacceptably high. We are an island and really we're not making full advantage of the fact that we are surrounded by sea. We should be doing far better, and the figures are appalling."
Mr Vaz told the BBC the "astonishing" figures "basically show[ed] that our border is not secure".
"The government keeps maintaining that they have got water-tight security at our borders," he said.
"If 27,000 people have been arrested for entering the country illegally by our police forces, then it shows that this problem is even worse than we had anticipated and we expect urgent action to be taken."
Mr Vaz said the problem meant "greater pressure" on the UK's police forces, as they were "having to do the work of border security". More resources were needed, he added.
Dover's Conservative MP Charlie Elphicke has called for further patrols in the Channel.
He said: "We need to not just dismantle the Jungle at Calais.
"We need to deal with the camps at Dunkirk and elsewhere and by the Channel ports. We also need to deal with the problem of people-trafficking by small craft.
"That's why I've been calling for a marine-led new Dover patrol to make sure that the English Channel is kept safe and secure."
The Home Office said where someone is found to have no right to remain in the UK, it will take action to remove them.
"As part of the ongoing action we are taking to secure our borders, we have invested tens of millions of pounds to bolster security at ports in northern France," a spokesman said.
"We are also committed to finding long-term solutions to the problem of illegal migration, which is why we created the Organised Immigration Crime Taskforce last year to work with law enforcement and international partners to target the organised crime gangs behind people smuggling."
There were "clear signs" that the action was working, he added.


Two men have been jailed for five years each for extorting £60,000 and attempting to extort £375,000 from a Fife property developer.

John Cowbrough, 47, from Airdrie, North Lanarkshire, and James Wilson, 53, from Tillicoultry, Clackmannanshire, were jailed at the High Court in Edinburgh.
They were found guilty last month of extortion between 1 January 2013 and 1 March 2013.
Between 22 April 2014 and 9 May 2014 they attempted to extort £375,000.
They sent their victim, a property developer from Inverkeithing, anonymous letters in which they threatened to kill members of his family unless he paid £60,000. The letters were spelled out with letters cut from newspapers.
They then made anonymous phone calls in which they pretended that the letters had been sent to him by dangerous criminals and the threats would stop once the funds had been handed over. They instructed him where and when to deposit the money.
The property developer then confided in Wilson, who was a work colleague and friend of 20 years, unknowing that he was in fact behind the threats.
Wilson offered his services as a courier, telling his victim he would safely transport the money to those who were demanding it.
The property developer agreed to this plan and handed over the £60,000 which was then kept by Wilson and Cowbrough.
Between 22 April 2014 and 9 May 2014, the pair again attempted to extort the property developer, this time sending anonymous hand-stencilled letters threatening violence against him and members of his family unless he paid £375,000.
Again the property developer received numerous anonymous telephone calls, promising that the threats would stop once the money had been handed over.
Becoming concerned about the level of their knowledge of his movements, the property developer reported it to the police.
Following their conviction, proceeds of crime actions have now begun against the pair, and are next due to call for a first Procedural Hearing on 8 February 2016 at the High Court in Edinburgh.
Kenny Donnelly, procurator fiscal for High Court cases in the East of Scotland, said: "Blackmail and extortion of this sort can have a profound financial and emotional impact on its victim.
"I would encourage anyone who receives threatening material of this nature not to suffer in silence.
"Scotland's police and prosecutors will deal with any such allegations with the sensitivity they deserve, and will make every effort to ensure that the perpetrators are apprehended and brought to face the full force of the law."


So-called Islamic State say it was behind a bomb attack on a church in Cairo on Sunday in which at least 25 people were killed.

One of its fighters carried out the suicide attack on the Coptic Christian cathedral, the group said in a statement.
Egyptian President Abdul Fattah al-Sisi had earlier named the attacker as Shafik Mahmoud Mohamed Mostafa, 22.
Mr Sisi said the attack caused "pain to all Egyptians".
IS named the attacker as Abu Abdallah al-Masri.
President Sisi used his address at a service for victims on Monday to urge the government to amend the country's terrorism laws, which he said were "restricting the judicial system" in its battle to prevent such attacks.
He also declared three days of national mourning for the victims of the blast.
The Christian minority in Egypt has frequently been targeted by Islamist militants.
Egypt has seen a wave of attacks by militants since 2013, when the military overthrew President Mohammed Morsi, an elected leader who backed the Muslim Brotherhood, and launched a crackdown against Islamists.
Some of Mr Morsi's supporters blamed Christians for supporting the overthrow.


Nearly 100,000 children in England are living in temporary accommodation after being made homeless, new figures show.

At the end of June, 66,980 individuals or families were registered as having no home of their own - an increase of 12% from the same date last year.
Almost a third of them had lost a home in the private rented sector.
Homelessness charities blamed housing benefit failing to keep pace with rent rises - but the government said there was a "strong welfare safety net".
Most homeless families with children are living in self-contained accommodation - where there is sole use of a kitchen and bathroom - the government figures show.
But more than 2,500 are living in bed and breakfast accommodation - 25% higher than a year earlier.
Of those households, 830 have been in B&Bs for more than 6 weeks, 36% higher than a year earlier.
Samantha Ashby's children have never really known a permanent home.
About 17 years ago the family was evicted by a landlord who was selling up. The same thing happened again a few months ago.
Still on the waiting list for a home with Bexley Council that she says she's been on for six years, Mrs Ashby, 40, is in temporary accommodation above a shop in Northumberland Heath with her two teenage sons, Billy and Zack, and her five-year-old daughter Millie, who sleeps on a mattress on the floor of her bedroom.
"I do feel like we have spent most of our life living out of boxes and bags. We have never really had our own place," she said.
"It's been really hard. It leaves me feeling like a bad mum - I can't even keep a roof over my kids' heads.
"I would just like for me and my family to have the opportunity to rent a fairly-priced social housing property - somewhere that we can go and stay and not worry that someone is going to sell it and turf us out.
"It's OK for the people who have had the right-to-buy, but I just don't like that it's left people now without anywhere to go. The social housing that there was has gone. There's nothing left to borrow, let alone buy.
"I just want to wake up and find myself at home, wherever that is."
The figures showed that, in total, 99,080 children were among those living in temporary accommodation.
The statistics do not include rough sleepers but the most recent data suggests there were about 2,700 people living on England's streets in autumn 2014.
Hannah Gousy, of homelessness charity Crisis, said: "Unfortunately, what today's statistics are showing us is that 30% of people who are being accepted as homeless are homeless because they are losing their home in the private rented sector and unfortunately the cost of housing benefit simply isn't keeping pace with market rents and that is making it extremely difficult for people."
Javed Khan, chief executive of children's charity Barnardo's, called the figures a "national embarrassment".
He said: "Day in, day out, Barnardo's works with vulnerable families and young people who've been pushed into rent debt because of low wages.
"Benefits changes have left them unable to cover the costs of essentials."
Campbell Robb, chief executive of Shelter, said the figures painted a "grim picture of the devastating impact welfare changes and sky-high housing costs".
The Department for Work and Pensions said the number of households living in temporary accommodation was "significantly lower" than the peak in 2004.
"Temporary accommodation ensures no family is without a roof over their head," said a spokesman.
"We continue to spend around Â£24bn a year on housing benefit, so there is a strong welfare safety net in place."
In Scotland, 34,605 households applied for homelessness assistance in 2014-15.
In Wales, a total of 1,350 households were threatened with homelessness between April and June, according to the most recent statistics, and there were 1,935 households in temporary accommodation at the end of June.
A total of 18,862 households informed Northern Ireland authorities they were homeless in 2013-14. According to the latest figures, the number of households accepted as statutorily homeless was 9,649.


Worldwide cargo handling business Swissport is creating 100 new jobs in an expansion of its operations at Belfast International Airport.

Swissport said the jobs will include positions in passenger check-in as well as baggage and freight handling.
The salaries of the new posts average out at Â£16,000.
The expansion will bring its workforce at Belfast International to about 350, making it the biggest employer at the airport.
Swissport said its expansion was based on planned airline growth, with Ryanair due to begin operating a new hub at Aldergrove later this year.
"These jobs are demand driven," said the airport's operations director Alan Whiteside.
"The fact they do not depend on a single penny of support from the government means we are seeing a win-win for the wider economy and the taxpayer," he added.
Earlier this month, security company ICTS announced it was taking on 40 extra staff at the International, partly because of Ryanair's arrival.


Three people involved in last week's Islamist attack in Burkina Faso are still at large, French Prime Minister Manuel Valls has said.

The assault on a hotel in the capital, Ouagadougou, was claimed by al-Qaeda in the Islamic Maghreb (AQIM).
The death toll has risen to 30 after a French-Moroccan photographer died from her injuries.
Three gunmen were killed in Friday's operation, Mr Valls said. AQIM on Monday released their photos and names.
AQIM said the assault was carried out by the al-Murabitoun battalion led by Algerian jihadi Mokhtar Belmokhtar.
Six gunmen opened fire on unarmed patrons at the Cappucino cafe before taking refuge at the nearby Splendid Hotel where they held several hostages, the French PM told parliament.
Both places were popular with UN workers and foreign residents.
"Three were killed and three others were being sought," Mr Valls said.
Among the 30 killed were three French nationals, he added.
French special forces based in West Africa were involved in the operation to end the hotel siege in its former colony.
The others who are known to have died include:


Caledonian MacBrayne has formally signed a new £900m contract to continue operating the Clyde and Hebrides Ferries Network.

State-owned CalMac had competed with private firm Serco Caledonian Ferries Limited for the Scottish government contract to run the services.
CalMac already operates the routes on the west coast of Scotland, which include the inner and outer Hebrides.
It was named the successful bidder of the new contract in May.
The contract, which was awarded by the Scottish government's Transport Scotland, covers an eight-year period from 1 October.
The deal includes a separate contract which sees CalMac taking responsibility for ferry operations at 24 ports on behalf of Caledonian Maritime Assets Ltd (CMAL).
CalMac managing director Martin Dorchester said: "Now that the contracts have been signed we can start to share information with staff and customers about our ambitious plans to transform the experience of ferry travellers during the lifetime of the contract."


LeBron James will be the NBA's highest paid player next season after agreeing a reported $100m (£77.2m) three-year contract with the Cleveland Cavaliers.

The American is expected to sign for $31m (£23.9m) next campaign, rising to $33m for 2017-18, his agent has said.
James led the Cavaliers, his hometown club, to their first NBA championship last term after rejoining in 2014.
"I can't be more excited than this opportunity once again, to defend our crown, defend our title," he said.
In a video posted on sports news site Uninterrupted, James added: "We all know last year as a magical, inspiring, all the words you can come up with, it was an unbelievable season."
James, four times the NBA's most valuable player, won two championships for the Miami Heat before returning to the Cavaliers.
His agent Rich Paul released the details of the contract - which is yet to be completed - to ESPN, with James reportedly earning a rise of more than $8m for next season.


Championship side Brighton & Hove Albion have signed defender Ben Hall from Motherwell for an undisclosed fee.

The 19-year-old, who made 19 appearances for the Scottish Premiership side last season, has agreed a two-year deal at the Amex.
Centre-back Hall, who is a Northern Ireland Under-19 international, will initially join Albion's under-21 squad.
"Ben is an excellent young prospect," Seagulls boss Chris Hughton told the club website.
"His challenge is not only to progress but to be ready to make that step up into the first-team squad."
Motherwell say Hall, who joined Well from Dungannon Swifts in 2013, was offered several new contracts to stay at Fir Park.
"We have been in discussions with Ben for the best part of five months," manager Mark McGhee told his club website.
"However, we have always been conscious that this may happen and, as such, have been working on a replacement, which we hope to announce soon."
Find all the latest football transfers on our dedicated page.


The Swiss banking industry has released the names of holders of dormant accounts, in the hope they will come forward to claim over $44m.

More than 2,600 names were released on dormantaccounts.ch.
New Swiss banking regulations mean that if an account containing more the 500 Swiss Francs ($505; Â£335) has been left dormant for 60 years, ownership of the funds reverts to the state.
Around 80 safety deposit boxes have also been gathering dust since 1955.
The deadline for submitting a claim is one year from the date of publication of the account holder's name.
"By publishing this information, the banks are making a last attempt to re-establish contact with the customer," said Claude-Alain Margelisch, chief executive of the Swiss Bankers Association.
He added that the new regulations - which took effect in January - also create legal clarity about dormant assets.
The banking lobby group said that banks may charge their costs to claimants who file clearly unfounded requests.


A section of Edinburgh's Princes Street has reopened following an incident at the Scott Monument.

The city centre road was closed from Waverley Bridge to the Mound for more than an hour.
Officers were called to the 200ft Gothic tower in East Princes Street Gardens at about 14:00.
A Police Scotland spokeswoman said: "We were called because of reports of concern for a person at the monument."
A woman involved in the incident was said to be safe and well.
A spokesman for Police Scotland said: "We can confirm that the incident at the Scott Monument came to a peaceful conclusion at around 15:30."
"Officers are now working to reinstate traffic in and around the area of Princes Street."


Manchester United manager Jose Mourinho is "humiliating players" by questioning their commitment, says ex-Blackburn striker Chris Sutton.

Mourinho has appeared to criticise the desire of Luke Shaw, Chris Smalling and Phil Jones to return from injuries.
Sutton told BBC Radio 5 live Mourinho was "running the risk of turning the dressing room against him".
"To call them out for not playing through the pain barrier is deeply unfair," he added.
Left-back Shaw will miss the remainder of the season with a foot injury he picked up during United's 1-1 draw with Swansea on Sunday.
Neither Jones, who has a toe injury, nor Smalling, who has a knee injury, have played for United since 19 March but are close to a return to first-team action.
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"Managers I have played under would say things in the dressing room but back you in public. Mourinho just shoots from the hip. I think further down the line that leads to trouble," said Sutton.
"Having said that, in my opinion, what he is saying to the Manchester United board is, 'I don't want these players at the club. I need to replace them'. He is not daft - he knows what he is saying."
Mourinho has appeared to indirectly criticise the trio in recent weeks.
Speaking of Shaw in April, he said: "I cannot compare the way he trains and commits, the focus, the ambition. He is a long way behind."
After Sunday's draw with Swansea, he said during a news conference: "I prefer not to speak about Phil Jones and Chris Smalling.
"I prefer to speak about Juan Mata giving everything to be available. I am grateful for that."
The Red Devils face La Liga side Celta Vigo in the Europa League semi-final first leg on Thursday.


Police have begun a murder inquiry after a man was subjected to a "violent assault" at a flat in Fife.

Duncan Banks, 39, was found dead at the property in Skye Road, Dunfermline, at about 17:00 on Monday.
Following a post-mortem examination officers confirmed they were treating his death as murder.
Mr Banks' family said he was a popular character with a "heart of gold who wouldn't hurt a fly" and they had been left "utterly devastated" by his death.
Det Ch Insp Keith Hardie, of the Major Investigation Team, said: "Following the conclusion of a post-mortem I can confirm that the death of Duncan Banks is being treated as murder.
"I ask anyone who was in the area of Skye Road between 11:00 on Sunday, September 27, and 17:00 on Monday, September 28, and who noticed any unusual behaviour to come forward.
"Mr Banks was the victim of a violent assault and we are committed to tracing anyone who was involved in his death.
"Such acts of violence have no place in society and I would again urge anyone who has any relevant information to contact police immediately on 101. Alternatively, information can be passed anonymously through the charity Crimestoppers on 0800 555 111."
Mr Banks' family  issued a statement through Police Scotland, which said: "Duncan was a beloved son and a much-loved brother and uncle and we have all been left utterly devastated by his death.
"He was a very popular character, who had a heart of gold and wouldn't hurt a fly.
"Whenever he could, he would try to help his friends and family with any problems they had.
"We have been overwhelmed with the support we've received from our friends and the local community during this awful time and we are all so grateful for the messages of sympathy we continue to receive."
West Fife Area Commander Ch Insp Irene Ralston said: "I want to reassure the local community that, although this is a serious and violent crime, it is not a common event in Fife and we are doing everything in our power to bring whoever is responsible to justice.
"We have high visibility patrols in the Skye Road area and have set up an incident bus.
"Anyone who has concerns is welcome to speak to an officer there."


A painting described as the definitive portrait of Jane Austen is to be sold at auction in December.

The watercolour, which has rarely been seen in public, has remained in the Austen family since it was created.
Estimated to fetch up to Â£200,000, it was commissioned by the author's nephew, Rev James Edward Austen-Leigh, in 1869 to accompany his biography of the author.
An engraving of the painting will appear on the new Â£10 note from 2017.
The portrait was based on the only confirmed portrait of Austen made during her lifetime by her sister Cassandra.
Austen-Leigh did not think his aunt's depiction was a true likeness however, so commissioned Maidenhead artist James Andrews to create a more "satisfying version" based on his own memories.
In his biography, titled Memoir of Jane Austen, he described her as "a clear brunette with a rich colour".
"She had full round cheeks, with mouth and nose small and well formed, bright hazel eyes, and brown hair forming natural curls close round her face...she never was seen, either morning or evening, without a cap."
Dr Gabriel Heaton from auction house Sotheby's said Andrews' portrait - which became the accepted image of Austen and spawned many reproductions - was "part of our cultural history".
"This is the most important likeness of Jane Austen ever likely to appear on the open market," he said.
"The painting was commissioned for the first full-length biography... which was crucial in transforming her from a novelist into a national figure.
"The portrait gave readers an image with which they could identify and which even seemed to embody the character of her work."
The painting will be sold at a Sotheby's London auction on 10 December.


Summer signing N'Golo Kante made his first appearance for Chelsea as two goals from Oscar saw the Premier League side beat AC Milan 3-1 in Minneapolis.

The International Champions Cup friendly was the first sporting event to be held at the new $1.1bn (£830m) home of NFL side Minnesota Vikings.
Bertrand Traore headed the opener for Chelsea before a Giacomo Bonaventura free-kick drew the Italian club level.
Brazil midfielder Oscar's brace sealed it for Antonio Conte's side.
Kante, who left Premier League champions Leicester for a fee in the region of £30m, came on as a second-half substitute.
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Chris Woakes took 3-31 as England bowled Sri Lanka out for 288 to take a grip on the third Test at Lord's.

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Woakes took the key wickets of Kusal Mendis and Angelo Mathews and was well supported by Steven Finn's 3-59 as the tourists slumped from 162-1 overnight, as only Kusal Perera (42) resisted.
Under-pressure England man Nick Compton was out for 19 as the hosts lost three wickets for five runs in reply.
But they closed day three on 109-4, leading by 237.
Jonny Bairstow was out for 32 before the close, one of three wickets for the impressive Nuwan Pradeep, but Alex Hales remains unbeaten on 41.
Victory in this match will give England the series 3-0 having won the previous Tests at Headingley and Chester-le-Street.
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For much of this series, and indeed recent series, England's main wicket-taking threat has come from the enduring class of James Anderson and Stuart Broad.
But instead it was Woakes and Finn who took centre-stage as Sri Lanka's habit of losing wickets in clusters once again bedevilled them.
Woakes should have had a wicket with his first ball on Friday - only to see Dimuth Karunaratne dropped by Bairstow - but this time he did strike with his first delivery of the day, pinning Mendis lbw for 25, before he had Mathews caught at slip for three.
Finn, bowling with by far his best rhythm of the series, then had Dinesh Chandimal lbw for 19 and enticed Lahiru Thirimanne to edge to slip for 17.
Their form will pose a dilemma for the England selectors, with one of the two likely to lose their place when all-rounder Ben Stokes returns from injury.
Having established a 128-run first-innings lead, England were forced to turn to an unfamiliar opening combination, with Alastair Cook unavailable having gone for a scan on a knee injury sustained at silly point.
However, Compton's promotion up the order to the position in which he played his first nine Tests for England did little to revitalise his fortunes, as he nicked Eranga behind.
Having mustered just 51 runs at an average of 12.75 in this series, and with number threes like Scott Borthwick and Tom Westley scoring heavily in county cricket, the likelihood must be that 32-year-old Compton's 16th Test will be his last.
He was swiftly followed back to the pavilion by Joe Root - bowled by a scuttler from Pradeep - and, one ball later, Vince, bowled shouldering arms to the same bowler.
With 54 runs at 13.5, Vince has scarcely fared any better than Compton in this series, and while he will surely be given the series against Pakistan, he still has much to do to prove himself in Test cricket.
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It has been a tumultuous 24 hours for England captain Cook, who was made a CBE in the Queen's Birthday Honours list announced on Friday.
But he was hit on the knee by a lusty drive from Perera and went to hospital for a scan, meaning that - for the first time since 2006 - England opened the batting in a home Test without the Essex man.
However, the scan revealed nothing more sinister than bruising and Cook is expected to bat in the morning.
England bowler Steven Finn on Sky Sports: "We've had a very good day. Only taking one wicket yesterday, to come back and bowl them out for 288 was a very good effort. To be 237 runs ahead and the ball is spinning a little bit...
"If we can get far enough ahead and get an unassailable lead, we can put Sri Lanka under some pressure.
"I've felt good in this game, back to normal. It's good to contribute again. I was maybe feeling for it a bit. Once I got into the spell I thoroughly enjoyed it."
Former England batsman Geoffrey Boycott on BBC Test Match Special: "The England top order has failed. The middle-order batting and the bowlers get England their wins. It doesn't fill you with confidence.
"Keep Vince, they have to give a player a good chance. He's got a bit to do. Compton, sadly, they will have to pick somebody else. The selectors have to identify someone and say 'his chance is now'."


A seal spotted on a Norfolk beach with a wound around its neck has vanished and its fate is likely to "remain a mystery", wildlife experts have said.

The RSPCA had planned to wait until the end of the winter breeding season before trying to catch the seal at Horsey beach.
However, he has not been seen since late December.
Alison Charles, RSPCA hospital manager, said: "We will just never know now if it's a happy or sad ending."
It was believed the bull seal's deep wound was caused by netting.
Experts said it had been too risky to try catching him for treatment when he was surrounded by females until the end of the breeding season in late January.
Any action could also have disturbed mothers with their pups.
If he was darted, there was a danger he could bolt into the sea, lose consciousness and drown.
Peter Ansell, from the Friends of Horsey Seals group which monitors the colony, said: "He might be dead or he might have swum off to pastures new.
"It's highly unlikely we will see him again - it will remain a mystery."
The RSPCA had assembled a team and equipment at its East Winch centre near King's Lynn to try to catch their first wounded seal.
Ms Charles said: "I recently went to inspect two females who also had been seen with netting around their necks, but it had fallen off.
"Their wounds were healing and it seems it may have been possible for them to use their flippers and nails to it.
"The bull seal's wounds could also have healed."
Volunteers counted 1,018 pups at Horsey this winter - a record for the colony since seals began using the public beach north of Great Yarmouth in 2003.


Melissa Reid says she plans on competing at the 2020 Paralympics after winning a bronze medal in the PT5 Para-triathlon in Rio.

The 25-year-old from Cornwall left it late to finish third alongside her guide Nicole Walters.
"At one point we didn't think we were going to do it, but we managed to get it on the line," Reid told BBC Sport.
"I'd love to go to Tokyo - it's one of my favourite places in the world and I think I'm young enough to compete."
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Reid, a former world champion and European silver medallist, was competing in the first ever Para-triathlon at a Paralympic Games.
"My dad didn't think I'd finished third because we were in fourth place up until the last 100 metres," she added.
"He sat back and it took him about half an hour to realise that we'd crossed the line in third place."


Thieves have stolen nearly $250m (Â£165m) of oil from a single pipeline this year, Nigeria's state oil company says.

The Nigerian National Petroleum Corporation (NNPC) said half a billion litres were taken from the pipeline that runs north-east from Lagos.
Long queues have formed at petrol stations across Nigeria in recent days.
Governments blame pipeline vandalism and theft in the oil sector for fuel shortages and damaging the economy.
An NNPC subsidiary told a Senate committee that "incessant hacking" of the System 2B pipeline had "made the task of providing seamless flow of petroleum products to retail outlets more burdensome".
The pipeline stretches 250km from the financial hub Lagos to the city of Ilorin.
The company said it was working to resolve the issue.
"We have been pushing 35 million litres every day to the market and there's no reason why there shouldn't be fuel," said Esther Nnamdi Ogbue, managing director of the Pipelines and Product Marketing Company, a subsidiary.
She blamed "sharp practices" such as hoarding in some areas.
Nigeria is Africa's biggest oil exporter, but a lack of refining capacity means drivers rely on imported petrol and there are frequent fuel shortages.
In May the country was brought to a virtual standstill after importers shut depots over subsidy payments.
President Muhammadu Buhari has been urged to scrap the subsidy scheme, which critics say is rife with corruption, but a previous attempt to stop the payments led to violent mass protests in 2012.
However, in August NNPC managing director Emmanuel Kachikwu said the subsidies were an unsustainable drain on the economy, which has suffered as global oil prices have fallen.


A proposal to use empty buildings in Oxford as temporary homeless shelters has been backed by councillors.

The city council gave its support to the plan after squatters from the Iffley Open House campaign group repeatedly occupied disused properties.
They included a vacant car showroom, an Oxford University building and a former Italian restaurant.
Campaigner and former councillor Elise Benjamin said the squatters had raised awareness of homelessness in the city.
The council motion said the decision was taken because of the growing number of rough sleepers, and the "significant number of long and short-term vacant buildings in Oxford".
It will now commission a report by September into how empty properties could be made available for use as temporary homeless shelters.
The group, which included about 20 homeless people, had to leave the buildings they occupied after several court orders were granted against them.
Ms Benjamin said: "There was an astonishing public response, so positive, so many many people contributing their time and donations.
"We believe that can continue and with the council supporting us we have an even better chance that there will be that same response again."
On New Year's Eve, the group moved into a car showroom on Iffley Road owned by Wadham College.
They were evicted in February and they occupied Osney Mill, which is owned by Oxford University.
A court order was granted to repossess the property in March, and the group moved to a former Italian restaurant in Summertown, then empty flats above a Sainsbury's in Cowley Road.
The have since left for health and safety reasons and are believed to be staying with friends.


A woman who added Skywalker as a middle name has had her passport cancelled after being told her application was "frivolous".

Laura Matthews, 29, was told her signature - "L. Skywalker" - infringed a trademark in July this year.
She was issued with the document several weeks later, after threatening to take legal action.
But she has now been told the passport was issued in error and has been cancelled.
Ms Matthews told the BBC the decision has left her feeling "upset, frustrated and disappointed".
A Home Office spokesman said: "Protecting the integrity of the UK passport is vital and we do not accept a change of name for frivolous reasons."
In a letter to Ms Matthews, the Passport Office said its "published guidance provides that we will refuse to recognise a change of name... if it is made for a bet or frivolous purpose.
"Additionally, in your case, the signature used in the passport is different to your surname and by your own admission was done for 'a laugh'".
"Regrettably, an error was made in issuing your passport," the letter said.
"I am sorry that the error was made but I have to inform you that your passport will be cancelled."
Ms Matthews, from Southend in Essex, added the middle name using a deed poll in 2008 "for a bit of fun".
She had not renewed her passport since adding the moniker, and experienced several weeks of delays when she tried to do so in April.
She was told the delays were because her signature "infringed a trademark".
Her passport was issued at the end of August after she contacted a law firm specialising in intellectual property law and said she would take legal action unless her application was approved.
Ms Matthews said this was the fourth time the Passport Office had changed its mind about her case.
"Now I'm not sure if it's my signature they have a problem with, or my middle name," she said.
"All I know it's extremely disappointing that I've been let down again by an organisation which doesn't seem to know if it's coming or going.
"I don't think I'm going to be able to fight it. I don't know what else I can do."
The Home Office spokesman added: "We have apologised to the applicant and agreed to meet the cost of a new passport in a name that meets the published guidance."


A seven-year-old boy has died after being hit by a van in Moray.

Police said the child was struck by a red Renault Master van on Brechan Rig in Elgin at about 17:30 on Friday.
The van was being driven by a 46-year-old man who was uninjured in the incident. The identity of the child has yet to be released.
Police have appealed for witnesses to the crash or anyone who saw the van in the time before the accident to come forward.
Sgt Steve Manson said, "My thoughts, and that of my officers, are very much with the family and friends of the seven-year-old boy who sadly died in this tragic collision.
"I would appeal to anyone who may have seen the crash or who may have seen the red Renault Master van shortly beforehand and who hasn't yet spoken with police to do so as a matter of urgency to help us piece together exactly what happened."


Republican presidential candidate Ben Carson has risen up in the polls to nearly tie frontrunner Donald Trump.

Coverage of the 2016 race for the US presidency has been largely focused on Donald Trump, who has dominated the polls and the headlines with his larger-than-life persona and controversial views on immigration. But a very different candidate is slowly gaining on him.
On Tuesday, news broke that Dr Ben Carson, a retired neurosurgeon popular with evangelical voters, has just about tied Trump according to a new New York Times/CBS News poll. Carson strikes a dramatically different political pose, often noted for his calm demeanour and professorial speech style.
Carson's support leaped from 6% to 23% among likely Republican primary voters, whereas Trump increased his margin only slightly from 24% up to 27%.
However, both men have made much of their status as political outsiders.
"I'm not politically correct," Carson has said many times. "I am not a politician."
So who is he?
Early life
Ben Carson was born in 1951 in Detroit, Michigan. His mother raised him and his siblings after their father left the family when Carson was 8. He credits his mother, Sonya, with prioritizing his education even after he struggled with his grades.
Carson eventually went to Yale, where he met his wife Candy.  Then he studied at The University of Michigan School of Medicine. He did his residency at Johns Hopkins Children's Center in Baltimore, Maryland, where he became the director of paediatric neurosurgery at just 33 years old. He pioneered techniques for operating on brain cancer and epilepsy.
Carson gained international fame in 1987 for performing the first successful surgery on twins conjoined at the head.
The pace of his work slowed when he was diagnosed and then successfully treated for prostate cancer in 2002.
Best-selling author and television fame
He has written a number of books including a 1990 memoir called Gifted Hands. In 2009, it became the basis for a movie on the television network TNT in which Carson was played by Cuba Gooding Jr.
He also spent much of his time speaking to classrooms of young students in Baltimore.
"I can't even count how many times I saw Ben Carson when I was a kid," writer Ta-Nehisi Coates once told to GQ magazine, "Any time anyone wanted to bring out any sort of inspirational figure for young black kids, especially young black boys, in Baltimore, you turned to Ben Carson."
The books also lay out Carson's strong religious convictions. He was raised a Seventh Day Adventist and these religious beliefs also inform many of his political views.
Political aspirations
Carson began drifting toward politics with the publication of his 2012 book, America the Beautiful: Rediscovering What Made This Nation Great, which was critical of the election of Barack Obama. He then rose to fame in the conservative political arena after giving a speech at a 2013 National Prayer Breakfast that was unexpectedly critical of Obama's health care plan.
The president was sitting just two chairs away, and Carson was exuberantly lauded for his gall by Rush Limbaugh and Sarah Palin. In a subsequent speech, he called Obamacare the "worst thing that has happened in this nation since slavery".
Later that same year, he retired as a surgeon.
A political action committee named "Draft Carson" began quietly amassing a $14m war chest, and in May 2015, Carson announced he would enter the presidential contest as a Republican. He has credited the draft movement as a major reason he jumped into politics.
Conservative and controversial views
Though his affect may differ from Trump's, Carson also has a history of controversial statements which have landed him in hot water.
While he concedes that gay marriage is now "the law of the land," at one point he told an interviewer that marriage should be between a man and a woman, and that "no group, be they gays, be they Nambla, be they people who believe in bestiality, it doesn't matter what they are, they don't get to change the definition". He also once said that homosexuality is a choice and said prison inmates were evidence of this. He subsequently apologised forboth comments.
Recently, he made headlines in California by denying that there is compelling evidence to support climate change. He identifies as pro-life and has supported a ban on abortions after 20 weeks. He says there is no contradiction between this and the fact that his past medical research was done using fetal tissue.


Striker Darren Bent was relieved to score with his first touch in six weeks to keep Derby County's unbeaten run intact ahead of the play-offs.

Bent rescued a point for the Rams against Sheffield Wednesday, heading in the equaliser a minute after coming off the bench on Saturday.
Derby, already assured of a play-off spot, are unbeaten in five games.
"The main thing is that we go into the play-offs full of confidence and not losing games," Bent said.
Former England striker Bent said falling at the first hurdle of the play-offs against West Ham in his last season with Ipswich Town in 2004-05 was a harsh early lesson in his career.
"A fair few years ago now at Ipswich, our season had gone because we only managed to win one out of our last five games. We went into the play-offs with no real confidence," Bent told BBC Radio Derby.
As for his own personal form, Bent was pleased to make an impact as a substitute having not featured since Derby's 3-3 draw with Rotherham in March.
The goal was the former Aston Villa, Sunderland and Charlton forward's first since netting the winner in Derby's 2-1 FA Cup third-round win against League Two side Hartlepool in January and only his second in the Championship this season.
Bent scored 12 goals in 17 games during a loan spell at the iPro Stadium from Villa last season, before signing a full-time deal last summer.
"The boys have been joking it was my first touch in three months, it was nice," Bent said.
"It was a while for that one to come. It's been difficult to get minutes on the pitch with the team playing really well, Chris Martin at the top of his game and the two wide men playing well.
"To be match sharp is impossible if you play a few minutes every four or five weeks, but when you do get on the pitch you want to help the team out, and it worked."


Leeds United have promised to give fans who buy a season ticket for 2016-17 a refund of up to 50% - if the club fail to reach the Championship play-offs.

Fans who buy a ticket before the end of May will receive 25% of their money back if the club sell less than 15,000 tickets by the end of July or 50% if they sell more than that amount.
Leeds have not finished in the top six of the second tier since 2006.
The Elland Road side can not finish in the play-off places this season.
The club said in a statement: "We are more determined than ever to gain promotion from the Championship and are fully committed to doing everything we can to return this great club to the Premier League in 2016-17.
"With the full support of our fans, we believe we can achieve this goal next season."
Leeds have not played in the top tier of English football since relegation from the Premier League in 2004.
Head coach Steve Evans said on Monday that he believed he was the right man to lead the club back to the top division.


Some of the world's leading cancer experts are gathering in Belfast.

They will discuss the latest findings in treatment, outcomes and prevention of the disease.
It is the first time that Northern Ireland has hosted the international conference.
Dr Anna Gavin of the Northern Ireland Cancer Registry, said the number of people diagnosed with the disease in NI was likely to increase.
"We have an aging population," she said.
"Some of the work that is going to be presented at the conference indicates that in the next 20 years, we are going to see two thirds  of an increase in the number of cancer patients that are diagnosed in Northern Ireland and across the UK.
"So that means we have to be smarter with the resources that we have."
About 11,000 people in Northern Ireland are currently living with cancer.
The conference, organised by Queen's University, will be attended by patients, charities and chief medical officers from the UK and Ireland.
Up to 500 people are taking part in the Belfast event at the Europa Hotel.
The Northern Ireland Cancer Registry is funded by the Public Health Agency in Northern Ireland and hosted by Queens University Belfast.


Somebody dies by taking their own life every 40 seconds, according to a significant report by the World Health Organization (WHO).

It said suicide was a "major public health problem" that was too often shrouded in taboo.
The WHO wants to reduce the rate of suicide by 10% by 2020, but warned that just 28 countries have a national suicide prevention strategy.
Campaigners said there needed to be more education in schools.
The WHO analysed 10 years of research and data on suicide from around the world.
It concluded:
It said limiting access to firearms and toxic chemicals was shown to reduce rates of suicide.
And that introducing a national strategy for reducing suicides was effective, yet had been developed in only a minority of countries.
Dr Margaret Chan, the director general of the World Health Organization, said: "This report is a call for action to address a large public health problem, which has been shrouded in taboo for far too long."
Social stigma attached to mental health disorders is known to stop people seeking help and can ultimately lead to suicide.
The WHO also attacked the reporting of suicide in the media, such as the details revealed about the death of Hollywood actor Robin Williams.
There was also a call for countries to provide more support for people who had previously made a suicide attempt as they were the most at-risk group.
Dr Alexandra Fleischmann, a scientist in the department of mental health and substance abuse at WHO, said: "No matter where a country currently stands in suicide prevention, effective measures can be taken, even just starting at local level and on a small-scale."
Jonny Benjamin, a suicide campaigner in the UK, told the BBC: "I think there needs to be much more public awareness around suicide and how to approach people that may be experiencing suicidal thoughts and feelings, too few of us know how to react when they see someone who may be at risk of taking their life or experiencing those thoughts and feelings.
"I think there needs to be much more public awareness, much more education in schools as well because, as statistics today have shown young people are especially at risk of taking their own lives."


Campaigners have welcomed Mauritania's new anti-slavery law which makes the offence a "crime against humanity".

It has also doubled the prison term for offenders to 20 years.
Activists hope the law will encourage more slaves to take legal action to secure their freedom and will encourage the courts to punish slave owners.
Mauritania abolished slavery in 1981, but activists say it is still widely practised and many in the West African country inherit their slave status.
According to the AFP news agency, the new law, passed on Wednesday, also criminalises "10 other forms of slavery", including forced marriage and handing a woman over to another man without her consent after the death of her husband.
Boubacar Ould Massoud, chairman of campaign group SOS Slavery, told the BBC it also provides for legal help for victims and enables them to seek compensation.
He said it was laughable to think that slavery did not exist in Mauritania.
"Often judges sympathise more with the slave owners than with the slaves. Slavery cases taken to court have up until now referred to the slaves as 'non-paid workers' or 'exploited and underage workers,'" he told BBC Afrique.
Anti-slavery activists in Mauritania also say they have faced harassment from the authorities.
AFP reports that three anti-slavery activists will be judged on appeal on 20 August in the central town of Aleg.
They include two members of the Initiative for the Resurgence of the Abolitionist Movement in Mauritania, a well-known non-governmental organisation.
They had been sentenced to two years in prison for "membership of an unrecognised organisation", the agency reports.
According to a 2014 survey by anti-slavery campaign group Walk Free, Mauritania has the highest number of slaves as a proportion of the population, at 4%.


Plans for new laws to protect people's rights online have been unveiled by the Liberal Democrats.

The proposed Digital Bill of Rights would protect personal information and impose tougher penalties on theft and illegal sale of data.
The party has pledged to introduce it within six months of a new coalition government.
Lib Dem leader Nick Clegg said the bill would "stop information about our lives being misused".
"We need to ensure that consumers, businesses, journalists and our children are protected in the online world," he said, launching a consultation on the plans.
The party said the bill would "beef up" powers for the Information Commissioner to inspect companies that break data protection laws.
It would give legal rights to compensation for consumers from companies which get people to sign up online to deliberately misleading or unreadable terms and conditions.
Other measures contained in the proposal include a code of practice for websites to correct defamatory or inaccurate information.
It would also enshrine in law the responsibility of the government to defend press freedom for journalists and citizen journalists online.
Julian Huppert, the Lib Dem's election candidate for Cambridge, told BBC Radio 4's Today programme that individual rights could be enforced without harming freedom of expression.
"Yes you want free speech but we've said for many, many centuries, that there should also be the right not to be defamed," he said.
"I think it is right to protect the citizen from having that sort of attack."
In 2013, more than 500 writers from around the world signed an open letter to the United Nations urging it to create an international bill of digital rights.
The letter condemned the scale of state surveillance after whistle-blower Edward Snowden leaked information about surveillance carried out by the US Government.


A fourth man has been found guilty for his part in the shooting of a man in an Edinburgh suburb.

Mohammed Ahmed, 29, also known as Jamal Saeed, was found guilty of murdering Mohammed Abdi in the Duddingston area in May 2013.
Last year Mohamud Mohamud, Cadil Huseen and Hussein Ali all received life sentences and were ordered to serve a minimum of 25 years for the murder.
Ahmed was found guilty at the High Court in Glasgow.
Judge John Morris QC deferred sentence on Ahmed, a first offender, until next month for background reports.
Ahmed fled the scene and flew to Somalia, where he was born, just days after the street shooting.
However, unknown to him he left behind at the murder scene his wallet. A bank card belonging to him was also found in the roof lining of the Volkswagen Sharan driven by the killers.
Mr Abdi was gunned down in what is understood to have been a feud over drugs and he died from a gunshot wound to the chest.
Iain McSporran, prosecuting, said: "The Crown's position is that there appears to have been an organised crime group consisting largely of Somalian males with London connections, operating in Glasgow and Edinburgh. "
They split into two rival factions shortly before the murder. Two days before the fatal shooting a message was sent saying: "The guns are coming out."
On May 26, 2013 the Sharan with the killers on board chased the Ford Focus containing Mr Abdi and his associates through the streets of Edinburgh.
It ended with the Sharan crashed into fencing beside a tennis court. After Mr Abdi  got out the Focus and was striking the rear of the Sharan with a baseball bat, he was shot with a sub-machine pistol from within the car.
The court heard that five shots were discharged from the machine gun before it jammed. Three of them hit Abdi - the fatal shot was through the chest.
The Crown's position is that it is not possible to say who fired the fatal shot. Ahmed was convicted of murder on an art and part basis.
Det Supt Kenny Graham, of Police Scotland, said: "The murder of Mohammed Abdi was a brutal killing and those involved showed absolutely no regard for human life or the safety of others in the area.
"Such incidents are thankfully extremely rare in Scotland and it is completely incomprehensible why these men chose a quiet suburban area of the capital to carry out such a barbaric act.
"Our investigation has been extensive and involved specialised officers working with authorities from other countries as well as across the UK."
In April and May last year, seven of the nine men accused of the murder of Mr Abdi appeared at the High Court in Glasgow.
During the trial Mohamud, 30, Huseen, 23, and Ali, 26, changed their pleas to guilty and the remaining accused had their pleas of not guilty accepted.


At least 14 people have been killed in a mass shooting in California involving up to three gunmen.

Officers said 17 people were also wounded in the attack at a social service centre in San Bernardino.
The gunmen, wearing military-style clothing and armed with long guns, opened fire at the Inland Regional Center, which helps adults with disabilities.
Witnesses said people locked themselves in offices as the gunfire rang out.
Hours after the attack, police hunting for the attackers riddled a black SUV with gunfire in a residential area several miles away.
San Bernardino Police Chief Jarrod Burguan tweeted: "Suspects are down, one officer wounded. Details still unfolding."
It is unclear if there is still a third suspect on the loose, but he warned residents in the area to stay inside.
The attack took place in a conference area where the San Bernardino County Department of Public Health was holding a social event, said Maybeth Field, the centre's president.
FBI officials said they do not yet know if it was a terrorist attack but local police said it might have been domestic terrorism.
"I think what they are getting at there, following the Paris attacks, is that they do not have any direct suggestion at this stage that this is an Islamist-style terrorist attack," said the BBC's James Cook who is at the scene. "Rather, if it is a terrorist attack it is perhaps some kind if home-grown terrorist attack here in the US."
He said that buses filled with people were being driven away from the scene, while the surrounding buildings remained closed with workers still sheltering inside.
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One man received a text from his daughter that said she was hiding inside the building, where she works.
Terry Petit told reporters his daughter wrote to him: "People shot. In the office waiting for cops. Pray for us. I am locked in an office."
President Barack Obama has responded to the shooting.
"One thing we do know is that we have a pattern of mass shootings in this country that has no parallel anywhere in the world," he said.
"There are some steps that we could take, not to eliminate all incidents, but to make sure they happen less frequently."
People were seen being led out of the health care centre which specialises in helping adults with disabilities like autism and mental health problems.
Some were wheeled away on stretchers with medics and police officers in attendance.
Marcos Aguilera's wife was in the building when it happened. He said a gunman entered the building next to his wife's office.
"They locked themselves in her office. They seen bodies on the floor," he told a local ABC News station.
His wife escaped unharmed.
The shooting happened less than a week after a shooting at a Planned Parenthood clinic in Colorado left three people dead and nine people wounded.


Edinburgh City overtook managerless Clyde and moved seven points clear of opponents Cowdenbeath by winning 2-1 at Central Park.

Clyde lost 2-1 at Montrose, while Stirling Albion beat promotion hopefuls Elgin City 1-0.
Montrose are now five points off fourth-placed Annan Athletic and nine behind Elgin.
City are ahead of Clyde on goal difference but have played two more games than the bottom two sides.
Dale Carrick fired Cowdenbeath in front against Edinburgh, who were level by the 17th minute through Dougie Gair's penalty following Liam Henderson's foul on Joe Mbu.
Josh Walker's strike in the second half put City ahead and Cowden then had Fraser Mullen sent off.
At Forthbank Stadium, Stirling and Elgin were tied at 0-0 until Sean Dickson struck in the third minute of stoppage time.
Clyde, playing their first match since manager Barry Ferguson's resignation, fell behind to Kerr Hay's early strike and Greg Pascazio fired Montrose's second.
Peter MacDonald pulled one back for Clyde after the break.


Families gathered at an airbase in Suffolk on Monday evening to welcome home their loved ones from Afghanistan.

Two Squadron RAF Regiment have returned from a six-month tour protecting the Nato airbase at Kandahar.
Aircraft brought the airmen home from Cyprus to Brize Norton before they travelled on to meet their families at their base at RAF Honington.
Their role in Afghanistan was to protect the key Nato airbase in southern Afghanistan from enemy attack.
However during the tour they lost two airmen.
Senior Aircraftman Luke Southgate was killed in February in an explosion north of the airfield.
On the day the airmen returned a short ceremony was held in his home town of Bury St Edmunds and a plaque was unveiled celebrating his life.
His family also planted a tree in his memory.
Last weekend Senior Aircraftman Kinikki Griffiths from One Squadron RAF Regiment was killed in a road accident while on patrol near Camp Bastion in Helmand province.
Described as an "exceptional" member of the regiment, he died just a few weeks before his 21st birthday.


The names of some of those who lost their lives in the huge fire at Grenfell Tower in west London have been confirmed.

At least 30 people were killed in the blaze.
Three of their names have now emerged.
Five-year-old Isaac Shawo has been described by his mother as a "beautiful boy".
He was a pupil at Saint Francis of Assisi Catholic Primary School and lived in Grenfell Tower with parents Genet Shawo and Paulos Petakle and brother Luca, who is three.
He reportedly got separated from his family in the smoke and the BBC has now learned that he died.
Artist and photographer Khadija Saye, 24, whose artwork is being shown in the Venice Biennale, lived on the 20th floor of Grenfell Tower with her mother, Mary Mendy.
Labour MP David Lammy confirmed her death, writing on Twitter: "May you rest in peace Khadija Saye. God bless your beautiful soul. My heart breaks today. I mourn the tragic loss of a wonderful young woman."
He said she was a "talented artist".  His wife is her employer and mentor. and she had been filmed for a BBC documentary.
Khadija's work in Venice is based on Gambian spiritual practices and is being shown in the Diaspora Pavilion. She had written on Facbeook: "It's been a real journey, tears shed, highs and lows, but mama, I'm an artist exhibiting at the Venice Biennale and the blessings are abundant!"
Syrian refugee Mohammed Alhajali, believed to have been 23, came to the UK in 2014 and was studying civil engineering while living in North Kensington.
Syria Solidarity Campaign said: "[He] undertook a dangerous journey to flee war and death in Syria, only to meet it here in the UK, in his own home."
He had been in a flat on the 14th floor with his brother Omar but the pair lost each other in their attempt to leave the building.
Mohammed then returned to the flat and tried to call family members in Syria but could not get connected to them, so spoke on the phone to a friend in the country for two hours while he waited to be rescued.
The brothers had been due to join the Syria Solidarity Campaign on Saturday to take part in The Great Get Together, celebrating the life of murdered MP Jo Cox and marking Refugee Week.


Russia and Angola have opposed moves at the UN Security Council to impose sanctions on a South Sudan general and a rebel commander, diplomats say.

The US had proposed a travel ban and asset freeze on army chief Paul Malong and rebel general Johnson Olony for continuing to fuel conflict.
The Russian ambassador to the UN said sanctions might aggravate the situation, AP news agency reports.
Fighting has continued in South Sudan despite last month's peace deal.
Both sides signed the agreement to end the 20 months of conflict under intense regional and international pressure.
The fighting between forces loyal to President Salva Kiir and his former deputy Riek Machar has forced more than 2.2 million people from their homes in the world's youngest state, which broke away from Sudan in 2011.
At least seven ceasefires have been agreed and then shattered - and US diplomats want to maintain the pressure to ensure the most recent deal succeeds.
Russia's UN ambassador Vitaly Churkin said he felt sanctions were not the solution after his country's talks with the foreign ministers of South Sudan and Sudan.
"The United States, very often they just say: 'Sanctions, sanctions, sanctions', and in some cases it severely aggravates the situation," AP quotes him as saying.
According to the Reuters news agency, Venezuela also requested that the sanctions proposal be put on hold.
A hold does not mean the proposal is dead, but it delays its consideration, the agency reports.
Angola wanted to give the parties more time to implement the peace deal, it said.
Fighting broke out in South Sudan in December 2013 after President Kiir accused former Vice-President Machar of plotting a coup.
Mr Machar denied the charges, but then mobilised a rebel force to fight the government.
On Tuesday, President Kiir reiterated his reservations about the deal in a televised national address as both sides accuse the other of breaching the ceasefire.
He again listed points such as the demilitarisation of the capital, Juba, and the appointment of a foreigner to monitor the agreement as "a violation of sovereignty".
However, he did express his commitment to the agreement.


Four teenage boys have been arrested in connection with a racist attack on a Polish man in Leeds.

West Yorkshire Police said the 28-year-old victim was seriously injured in the assault at around 21:35 BST on Friday in Alliance Street.
Four boys aged 14, 15 and two aged 16 have been arrested in the Armley and Bramley areas.
They were held on suspicion of racially aggravated grievous bodily harm and violent disorder.
Police are treating the attack as racially motivated due to comments made at the time.
Ch Supt Paul Money of West Yorkshire Police met Polish Consul General, Lukasz Lutostanski, on Monday.
The force and consulate are raising awareness among the Polish community of how to report hate crimes and police patrols have been increased in the area.
Ch Supt Money said: "Given the understandable concern that this incident has caused among people in Leeds, particularly the local Polish community, and the wider focus there has been on it, we have prioritised the investigation to ensure that we are doing everything we can to bring our enquiries to a successful conclusion.
"I want to reiterate that hate crime and hate incidents are completely unacceptable and will not be tolerated in any form.
"The police work closely in partnership with the council and other agencies to tackle hate crime and we encourage anyone who has been a victim to report those incidents."
Police enquiries are continuing to trace further suspects.


Mae manylion personol miloedd o staff meddygol yng Nghymru wedi cael eu dwyn o gyfrifiadur contractwr preifat.

Cafodd enwau, dyddiad geni, manylion dos pelydriad a rhifau Yswiriant Gwladol staff sy'n gweithio mewn unedau pelydr-X eu copïo ar ôl i hacwyr gael mynediad atynt yn anghyfreithlon ym mis Hydref.
Mae'r staff sydd wedi'u heffeithio yn defnyddio bathodynnau sy'n mesur eu cysylltiad â phelydrau-X.
Y cwmni sy'n prosesu'r data o'r bathodynnau ar ran y GIG yng Nghymru - Landauer - gafodd eu hacio.
Dywedodd y GIG yng Nghymru eu bod wedi lansio ymchwiliad i'r mater, ac mae BBC Cymru wedi gwneud cais am sylw gan Landauer.
Dywedodd rheolwyr bod radiograffwyr, glanhawyr a staff eraill yn y rhan fwyaf o fyrddau iechyd Cymru wedi eu heffeithio.
Mae'r rhain yn cynnwys tua 530 o weithwyr Ymddiriedolaeth GIG Felindre, sy'n rheoli'r bathodynnau mesur pelydrau yng Nghymru.
Mae 654 o staff Bwrdd Iechyd Betsi Cadwaladr hefyd wedi eu heffeithio, yn ogystal â nifer o staff deintyddol a milfeddygol.
Dywedodd rheolwyr y GIG bod y mater yn "siomedig dros ben", a bod cyfuniad gwahanol o fanylion personol wedi'u copïo, ac felly nad yw pawb wedi eu heffeithio yn yr un ffordd.
Mae manylion staff sy'n gweithio mewn ysbytai yn Lloegr a'r Alban hefyd wedi eu cymryd.
Dywedodd AC Ceidwadol Gorllewin Clwyd, Darren Millar ei bod yn bryder fod y manylion wedi cael eu cymryd ers 6 Hydref, ond nad yw rhai staff yng Nghymru wedi cael gwybod am y sefyllfa nes fis yma.
"Mae'r oedi wrth roi gwybod i'r rheiny sydd wedi cael eu heffeithio yn gwbl annerbyniol," meddai.
"Yn y cyfamser, gallai staff fod wedi gweithredu i amddiffyn eu hunain yn erbyn unrhyw ddrygioni gyda'u data, a chadw golwg am unrhyw beth anarferol."
Dywedodd cyfarwyddwr gwasanaethau canser gydag Ymddiriedolaeth Felindre, Andrea Hague eu bod wedi cael gwybod am yr hacio ym mis Ionawr.
Ychwanegwyd eu bod yn trafod gyda Landauer am yr oedi yn cael gwybod am y sefyllfa, a'u bod hefyd yn cynnal ymchwiliad i'r mater.
"Rydyn ni'n deall faint o bwysigrwydd y mae pobl a chwmnïau yn ei roi ar ddiogelu gwybodaeth bersonol ac, er nad yw hyn wedi digwydd o fewn systemau Felindre, mae'r digwyddiad yn siomedig dros ben," meddai Ms Hague.
Dywedodd Bwrdd Iechyd Betsi Cadwaladr eu bod wedi cysylltu gyda'r holl staff sydd wedi eu heffeithio, gan bwysleisio nad oes manylion unrhyw gleifion wedi cael eu cymryd.
Ychwanegwyd bod Landauer wedi trefnu y bydd credyd yr holl staff sydd wedi'u heffeithio yn cael ei fonitro, a hynny am ddim.


Tranmere Rovers have signed winger Elliot Rokka from Radcliffe Borough on a one-year contract.

The 21-year-old began his career in the Manchester United academy before moving to Macclesfield Town in 2013.
Rokka went on to join Radcliffe, where he scored 16 goals for the Northern Premier League Division One North side in the 2016-17 season.
"Elliot's an exciting player who will create chances and get fans off their seats," manager Micky Mellon said.


Eurotunnel is to abandon its plans to run freight-only ferry services between Dover and Calais after a Supreme Court ruling.

The court ruled on the Competition and Markets Authority's (CMA) ban on the train operator's MyFerryLink service.
In June Eurotunnel announced it was selling its two MyFerryLink passenger ferries, but retaining a freight ferry.
Now the company has announced its last ship, the Nord Pas-de-Calais, would be put up for sale.
The CMA said: "The Supreme Court has ruled that the Competition and Markets Authority (CMA) took the correct approach in assessing whether Eurotunnel's acquisition of three ferries and related assets formerly owned by SeaFrance should be treated as a merger."
The Eurotunnel Group said it was "extremely disappointed" by the decision.
"MyFerryLink had hoped to restart an activity with the freight-only ferry, Nord-Pas-de-Calais, which would have ensured 130 jobs," a spokesman said.


Controversial "treatments" by psychotherapists and preachers are being offered to gay people in Russia.

BBC Russian heard accounts of so-called cures, after it emerged that gay men were being persecuted in Chechnya, a mainly Muslim republic in southern Russia.
On Tuesday German Chancellor Angela Merkel said she had asked President Vladimir Putin to "use his influence to protect the rights of minorities", referring to the reports from Chechnya.
Homosexuality is not officially considered a mental disorder in Russia. But homophobia is common - not only in Chechnya.
Russia removed homosexuality from its list of recognised psychiatric conditions in 1999 - after the US had done so in 1973 and the World Health Organization in 1992.
Globally, scientists do not recognise any "treatment" of homosexuality as effective or required.
Psychotherapist Yan Goland, from the city of Nizhny Novgorod, says he has "cured" 78 gay and eight transsexual people using a method developed in the Soviet Union by his teacher, Nikolai Ivanov.
He told the BBC that the "treatment" lasted between eight and 18 months, and longer for transsexuals.
"When a patient comes to me, I show them similar cases: how they were and how they are now. The patient is filled with hope that we can help, and understands they need to be treated," he said.
In the first stage, he aims to "extinguish" the individual's same-sex attraction. The hypnotherapy sessions can last up to eight hours. He also uses a mixture of psychoanalysis and identity therapy as a way of influencing a person's dreams.
The second stage is meant to forge an attraction to the opposite sex. He prompts his male patients to sexually objectify the women around them.
"I tell them: 'when you leave the session, walk down the street and take a look at all the young woman you see, take an interest in their figures and select the best.'"
Step three, Mr Goland says, involves sex with members of the opposite sex.
Yuri, 40, says he underwent the psychotherapist's "treatment" in the early 1990s, wanting to "wake up and be on the right path", but ended up with his sex drive in tatters.
"The result was, without doubt, negative if not damaging. It was catastrophic, if I'm honest."
Mr Goland is now 80 and says he is still "treating" people.
Read more on Russian LGBT issues:
'They want to exterminate us', says Chechen gay man
Chechen police 'torturing gay men'
Russia's mixed messages on LGBT
Anti-gay drive evicts Russian teacher
A Russian web search on "how to cure homosexuality" brings up various websites offering online consultations with doctors.
The Nikitenko brothers describe themselves as "psycho-hypnologists" and offer a two-month course of audio-hypnosis. One session costs 5,000 roubles (Â£68, $88).
Nikolai Nikitenko believes homosexuality is a type of obsessive-compulsive disorder (OCD).
"When someone watches pornography and has gay sex, they forge a new neural pathway in the brain. A guy from Vladivostok called me: he's 18 and said he was worrying for nine hours a day about becoming gay."
Their hypnotherapy aims to de-stress the patient and teach them the "right ways to behave and react".
The brothers boast they have already "treated" seven gay people who wanted to be straight and say there is "no chance of them relapsing".
But there are doctors in Russia with views closer to those of Western specialists and scientists worldwide.
"You normally become aware of your sexual orientation between 11 and 13 years of ageâ€¦ There are several different orientations and homosexuality is one of the normal variants," says psychologist Pavel Sobolevsky, who works with LGBT patients.
"You can't change your sexual orientation," he told the BBC - and that is what he tells clients who approach him over their sexuality.
Attempts to change your sexual orientation through psychotherapy can be damaging, he warned.
Various religious organisations are offering "treatments" for homosexuals.
Some refused to go into details, saying they would only divulge them to religious media.
But Pastor Yevgeny Peresvetov did speak. He heads the Protestant organisation "Vosstanovleniye" (meaning "rehabilitation" or "resurrection"). It promises to help gay people "reject" their sexuality.
The organisation's YouTube channel has accounts of two men who have "liberated themselves from sin" by "ridding themselves of homosexuality".
The pastor, wearing a smart suit and a Jesus portrait on his tie, leads Sunday services in a Moscow club.
He sees homosexuality as an addiction - like a drug - and symptomatic of a "spiritual hunger".
"Either the individual's father wasn't present, or was violent, or was only there on the periphery. Homosexuals find freedom when they find God as their father."
Some Russian families turn to religious institutions to "cure" children who have come out.
Maria, 27, was taken to church against her will by her family to "treat" her homosexuality when she was only 13. She had holy water poured over her while others read out prayers.
"I couldn't hear anything; I was bawling my eyes out. They kept on reading out prayers and forced me to go to church, where I was told that my attraction to other women came from Satan," she told the BBC.
"They covered me in holy water and forced me to drink it. Sometimes they hit me with rods. I feel like they broke my mind."
Yevgenia, a 19-year-old transgender woman born a man, described intolerant attitudes among doctors.
"The first doctor said: 'You just got carried away: look at you, you're a real man! You want to have surgery? Can't you just live like everyone else?'"
A second doctor told Yevgenia she was probably a gay man and an attention-seeker.
"He said I just had to resign myself to being a man," Yevgenia told the BBC.


Builders working near a school dug up a number of glass bottles containing "wartime incendiary devices".

A bomb squad was called to Wingfield Road, Trowbridge, after the bottles - thought to contain "old military flares" - were unearthed.
People living near the building site - opposite an entrance to John of Gaunt School -  have been told to leave their homes or stay indoors.
The fire service said it was unsure exactly what chemicals were involved.
More on this and other top stories from across the West
"We're dealing with an unknown hazard and have called the military who have more experience", a spokesman said.
The Army team is expected to detonate the devices before 20:30 GMT.
Dorset and Wiltshire Fire and Rescue said a large amount of smoke would be generated and people living in the immediate area should keep their windows and doors shut.


Plans for a museum celebrating the achievements of two-time Formula One world champion Jim Clark have reached another funding landmark.

Scottish Borders Council (SBC) has been successful in a first stage bid to the Heritage Lottery Fund for the project in Duns.
Development funding of more than £50,000 has been awarded to help work up a full bid for about £645,000.
The council has already committed almost £620,000 to the scheme.
Community fundraising aims to bring in a minimum of £300,000 towards the project.
It would see the existing Jim Clark Room in Duns expanded and enhanced to allow cars and trophies to be put on display.
A total project cost of about £1.65m has been attached to the scheme.
It is hoped the development could be completed by 2018 - the 50th anniversary of Clark's death at Hockenheim in Germany, aged just 32.
The driver was born in Kilmany in Fife, but raised in the Borders, and was crowned Formula One world champion in 1963 and 1965. He won a total of 25 grand prix races.


One of the best-known South Indian actresses, Gopishantha - better-known by her stage name Manorama, has died of a heart attack in the city of Chennai, her family members say.

She was 78 and had been ill for some time.
A comedian, singer and a stage performer, Manorama was a quintessential artist.
Although she mainly appeared in Tamil films, she also acted in other South Indian language movies and in Hindi.
Tamil media reports say she appeared in more than 1,000 films in a career spanning nearly six decades.
"She's a legendary actor. She could play any role. She's admired for ability to speak in different dialects of Tamil language to perfection," says Sampath Kumar, who reports on arts and culture for BBC Tamil.
While Manorama became famous for her comedy roles in films, she became a character artist in the later part of her career.
"The most difficult thing is to make people laugh. It is easy to make them cry," Manorama said in a newspaper interview.
She started acting in plays at the age of 12 and had appeared in more than 1,000 plays.
Her first break in movies came in 1958 when she acted in the Tamil movie Maalaiyitta Mangai.
After that she worked with some of the leading actors and playwrights of her day - five of whom went on to become chief ministers of Tamil Nadu and Andhra Pradesh states.
Very few women actresses have managed to continue their career in the Tamil film industry over so many years.
"If I had chosen to act only as a heroine then I would have disappeared from the scene long ago. So, I decided to take up comedienne roles, so I survived in the industry for nearly five decades," Manorama said in a BBC interview.
Manorama had won several awards including India's National Award for Best Supporting Actor in 1989.
Manorama was hugely popular in the southern state of Tamil Nadu and widely regarded as a cultural icon.


South Africa captain Jean de Villiers has retired from international rugby after being ruled out of the rest of the World Cup with a fractured jaw.

Centre De Villiers, who was injured during Saturday's 46-6 win over Samoa, played 109 times for his country.
That makes the 34-year-old Stormers man the fourth most-capped player in the history of South African Test rugby.
"Rugby will be poorer without Jean," said coach Heyneke Meyer. "He is a true ambassador for South Africa."
De Villiers said he knew as soon as he left the field on Saturday that he had played his last Test.
He added: "Injuries are part of rugby and I've had my fair share, so by now I know how to cope with them. It's very sad, but life goes on."
De Villiers said he would be "eternally grateful" for the time he had as a South Africa player.
"I would like to wish the team all the very best," he added. "I'm now their number one supporter.
"The last time I got injured in a World Cup match and had to go home was in 2007, also against Samoa, and that finished well for the Boks, so hopefully it will happen again."
South Africa won the 2007 World Cup by beating England 15-6.
Springboks coach Meyer, who has called up Jan Serfontein to replace De Villiers, said: "Jean is a true ambassador for South Africa and a person everyone in our country can be immensely proud of.
"He will go down as one of the greatest Springboks ever and, in my eyes, he is probably one of the best captains in the history of world rugby, who always put the team first and gave his time for any player, young or old without ever changing who he is.
"Jean enriched my life and I hold him in very high regard, as person and rugby player."
De Villiers captained the Springboks 37 times, a tally only bettered by John Smit (83).


Forthcoming rises to the National Living Wage may need to be delayed because of uncertain growth in the economy, small businesses have said.

The wage is currently scheduled to rise to £8.75 an hour by 2020.
But the Federation of Small Businesses (FSB) said that target may have to be reconsidered, following a string of poor economic data.
The FSB said real incomes, productivity and GDP growth were all falling, with only employment levels improving.
As a result, it said the National Living Wage (NLW) should rise from £7.50 an hour to no more than £7.85 next year.
"It's vital that the NLW is set at a level that the economy can afford, without job losses or harming job creation," said Mike Cherry, the FSB's national chairman.
"Cost pressures on small businesses are building, and with most recent economic indicators underperforming, we are now facing the reality that the NLW target may need to be delayed beyond 2020."
The Low Pay Commission is due to make its recommendations to the government on the National Living Wage in the Autumn.
It has to work out whether higher pay rates are affordable, or whether they could damage the jobs market.
The Chancellor, Philip Hammond, will announce the final decision in this year's Autumn Budget.
The FSB's latest research suggests that most small businesses are already paying their staff more than the National Living Wage, but that 43% of firms have had to increase pay rates.
Most small businesses are making lower profits as a result, but 39% have increased their prices to make the pay rises affordable.
The National Living Wage applies only to employees over the age of 25.
Workers younger than that are paid the National Minimum Wage.


Burglars broke into a high-value vault in central London and emptied up to 70 safety deposit boxes by climbing down the lift shaft, Scotland Yard said.

The raiders disabled a second floor lift and climbed down the shaft to enter the basement of Hatton Garden Safe Deposit Ltd at the weekend.
A heavy duty drill was used to bore holes into the 6ft (2m) thick vault walls reinforced with concrete.
Many of the deposit boxes are thought to belong to uninsured local jewellers.
Det Ch Insp Paul Johnson said there was a "chaotic" scene in the vault, where a number of tools had been left behind, including an angle grinder, concrete drills and crowbars.
One of the tools used was a DD350 drill worth about Â£3,500. Experts said it was likely the thieves made several holes until they had created a big enough space to get through, which would have taken an experienced operator several hours.
The area is known for its gold and diamond trade and many local jewellers used safety deposit boxes to store their stock in after they had finished trading for the day.
A lot of the company's clients may not have insured their deposit boxes against theft, Graeme Trudgill, executive director of the British Insurance Brokers' Association said.
He predicted local jewellers could be left millions of pounds out of pocket.
"One man tells me he's lost several hundred thousands pounds in the heist," BBC Home Affairs correspondent Danny Shaw tweeted.
The victim had apparently stored jewels and watches there for five weeks following his retirement.
The owners of the other boxes are being contacted to find out what else may have been stolen.
Michael Miller from Knightsbridge, London, said he "felt sick" that he may have lost up to Â£50,000 worth of uninsured jewellery, including an irreplaceable timepiece he bought when his son was born.
Police said there was no sign of forced entry to the building, which is shared by a number of other companies. Scotland Yard said it had not ruled out insider knowledge.
"We've just got the vault open and there's security boxes on the floor and it's covered with dust and debris," Det Ch Insp Paul Johnson told a news conference earlier.
He described it as an "organised" operation and said getting to the bottom of what happened would be a "painstaking and meticulous" process.
No arrests have been made.


A north west London hospital set to accept additional emergency patients is already operating at "maximum utilisation", a report has revealed.

St Mary's Hospital will take Hammersmith Hospital's patients when its accident and emergency department closes in September.
The NHS report said additional space could not be found before the change and the plans carried a financial risk.
MP for Hammersmith, Andy Slaughter, said it was "grossly irresponsible".
Health Secretary Jeremy Hunt announced in October plans to close Hammersmith Hospital and Central Middlesex's A&E departments as part of the Shaping a Healthier Future programme.
As part of it Hammersmith Hospital will lose its A&E capacity and become a specialist hospital, operating a 24-hour Urgent Care Centre (UCC) which generally cares for walk-in patients.
Patients requiring an ambulance will instead be taken to St Mary's in Paddington.
The Imperial College Healthcare NHS Trust report said: "The current capacity at St Mary's for acute admissions is already at maximum utilisation.
"[St Mary's] will receive an additional 25 ambulances and up to 15 UCC-referred patients a day converting to 13 admissions, and therefore plans for additional capacity are being developed."
But it added that plans to find additional space was "unlikely to conclude prior to the closure of the EU (emergency unit)".
Mr Slaughter said: "Closing Hammersmith A&E… with four months notice, and by their own admission that they are not ready with alternative services, is dangerous and irresponsible and we are going to do everything we can to stop that happening."
He added he had urged Hammersmith and Fulham Council to speak to the NHS Trust to "persuade them to go back and look at this again".
The report also said there was a "clinical risk in recruitment and a financial risk" as junior medical staff would have their contracts terminated on 6 August meaning the hospital would have to rely on locums for a month.
Dr Mark Spencer, deputy medical director for the NHS in London, said: "What we're doing in each case is moving the small teams of doctors that are managing the A&Es at Hammersmith or Central Middlesex and moving them to larger units to provide better care over 24 hours a day which is much better for patients."
Under the government's plans, nine hospitals in north-west London will be redesigned so the most serious emergencies can be dealt with at A&Es in Hillingdon, Northwick Park, West Middlesex, Chelsea and Westminster or St Mary's hospitals.
The Trust must now approve proposals to close Hammersmith Hospital and Charing Cross Hospital A&E departments on 10 September.


Low pay for artists could mean their work loses its "edge and relevance", according to the public body that supports the industry in Scotland.

Creative Scotland has called for a greater commitment to pay artists fairly.
The agency said people from wealthier backgrounds were more likely to become artists.
The Scottish Government said more needed to be done to ensure artists can realise their potential.
In its Arts Strategy, Creative Scotland called for action to help artists sustain themselves throughout their careers.
According to the report: "It is those from wealthier backgrounds that are most likely to consider entering into the arts professionally today.
"This trend carries real risks if UK culture becomes homogenized and disconnected from the breadth of society and loses its edge and relevance within the world today."
Creative Scotland said the strategy covered dance, literature and publishing, music, theatre, visual arts, creative learning and equalities, diversity and inclusion.
Leonie Bell, the director of arts and engagement at Creative Scotland said: "Artists, cultural producers and arts organisations are a central part of a healthy, innovative, and dynamic society. Art and culture sit at the heart of who we are as a nation."
Scotland Culture Secretary Fiona Hyslop said: "I welcome the publication of Creative Scotland's Arts Strategy with its strong identification of the strengths and opportunities for arts in Scotland but with a sense of realism of the challenges facing individual artists and what can and should be done to support them.
"We have a vibrant, confident arts scene in Scotland but we need to do more to ensure that artists and also young people in wider community can realise more fully their potential. "
Creative Scotland said it would stage a number of debates across the country over the next two years to discuss and promote the strategy.


A man who was left paralysed after a car accident has been able to walk for the first time in four years thanks to a bionic exoskeleton.

Abdul Aldhfeiry, 21, from Cardiff, broke his neck in the accident in Australia in 2012.
He can stand with assistance but now the Â£100,000 technology developed in the United States has allowed him to take his first steps.
The bionic legs have reactors to the body's movement.
"I feel really good," said Mr Aldhfeiry, who walked 119 steps in three minutes.
"It was very tiring but fun. Hopefully I can get to do it more.
"You lean to the left and you lean to the right. If you lean to the right and your left leg moves."
The suit, made by Esko Bionics, consists of a backpack with two batteries, two motors at the hips, two at the knees and the ankles are spring-loaded while there are sensors on the feet and throughout.
The equipment was used by patients receiving neuro-physiotherapy care at the Morrello Clinic in Newport on Wednesday.
A newer version will have electrodes which use the person's own muscles to help them walk.
Jakko Brouwers, the clinic's managing director, wants to be able to use the exoskeleton more frequently but the cost is a sticking point.
"We would like to be able to work in parallel with them [Esko Bionics] for the new model which is being developed," he said.
"We would also like to build on this to do research with universities to enable it to become available in this country."