British Labour MP Jo Cox has died after she was shot and stabbed in an attack outside her constituency advice surgery.
The mother-of-two was attacked by a man reportedly shouting "Britain first" early this afternoon in Birstall, West Yorkshire.
Temporary chief constable for West Yorkshire Dee Collins told a news conference: "I am now very sad to have to report that she has died as a result of her injuries."
The alleged gunman has been named locally as Tommy Mair, 52, who neighbours in Birstall have described as "a loner".
Ms Collins expressed her deepest condolences to the family and friends of Ms Cox, whose children are aged three and five.
She said: "Jo was attacked by a man who inflicted serious and sadly, ultimately fatal injuries. Subsequently there was a further attack on a 77-year-old man nearby who has sustained injuries that are non-life threatening."
She added: "This is a very significant investigation with a large number of witnesses being spoken to at this time.
"It's a large and significant crime scene and a large police presence with a full investigation is under way to establish the motive for this attack."
The death of Jo Cox is a tragedy. She was a committed and caring MP. My thoughts are with her husband Brendan and her two young children.
— David Cameron (@David_Cameron) June 16, 2016
Husband of Jo Cox calls for people to fight hatred
Ms Cox was attacked as she prepared to hold a routine advice surgery for constituents.
In a statement, West Yorkshire Police said officers were called at 12.53pm "to a report of an incident on Market Street, Birstall, where a woman in her 40s had suffered serious injuries and is in a critical condition."
"A man in his late 40s to early 50s nearby also suffered slight injuries. Armed officers attended and a 52-year-old man was arrested in the area," it said.
The murder shocked Westminster and led to the suspension of campaigning in the British referendum on EU membership.
Labour leader Jeremy Corbyn said the country would be "in shock at the horrific murder" of the MP, who was a "much loved colleague".
Prime Minister David Cameron said: "The death of Jo Cox is a tragedy. She was a committed and caring MP. My thoughts are with her husband Brendan and her two young children."
Home Secretary Theresa May said it was a "dreadful event" adding that Westminster had lost one of its "brightest and most popular" MPs.
Utterly shocked by the news of the attack on Jo Cox. The thoughts of the whole Labour Party are with her and her family at this time.
— Jeremy Corbyn MP (@jeremycorbyn) June 16, 2016
Eyewitness Clarke Rothwell, who runs a cafe near the murder scene, described the attack, saying: "He was shouting 'put Britain first'. He shouted it about two or three times. He said it before he shot her and after he shot her."
He said the gunman fired three shots, the final one at her head.
Britain First is the name of a far-Right group which said it was "not involved and would never encourage behaviour of this sort".
Another witness, Hichem Ben Abdallah said the alleged attacker was "kicking her as she was lying on the floor".
He said that after a bystander intervened, the man produced a gun, stepped back and shot Ms Cox.
Mr Abdallah, who was in the cafe next door to the library, told the Press Association: "There was a guy who was being very brave and another guy with a white baseball cap who he was trying to control and the man in the baseball cap suddenly pulled a gun from his bag.
"He was fighting with her and wrestling with her and then the gun went off twice."
He added: "I came and saw her bleeding on the floor."
Mr Abdallah said the weapon looked handmade and that the man who had been wrestling with the assailant continued to do so even after he saw the gun.
He said: "The man stepped back with the gun and fired it and then he fired a second shot. As he was firing he was looking down at the ground.
"He was kicking her and he was pulling her by her hair."
Mr Mair's house was sealed off by police who were guarding the property as forensic officers worked in the garden.
Neighbours said he had lived there for more than 30 years - on his own for the last two decades since the deaths of his mother and grandmother.
Ms Cox was elected to the seat of Batley and Spen at the last general election in 2015.
She was a Remain supporter in the referendum and both official campaigns suspended their operations as a mark of respect following the attack on her.
Her husband Brendan Tweeted a picture of her next to the River Thames, where they lived in a houseboat, shortly after the attack.
— Brendan Cox (@MrBrendanCox) June 16, 2016
Ms Cox graduated from Cambridge University in 1995 and worked as an adviser for former Labour prime minister Gordon Brown's wife, Sarah, and Baroness Kinnock.
She was a vocal advocate for the victims of the Syrian civil war and abstained in last autumn's contentious vote on allowing British military action in Syria.
Mr Cox, a former advisor to Mr Brown, spent Wednesday campaigning for the UK to remain in the EU.
He posted photographs of himself and the couple's two young children travelling along the Thames in a dinghy during a counter-protest against a pro-Brexit flotilla of vessels.
Meanwhile, Taoiseach Enda Kenny has described the attack as "an appalling crime on a public representative going about her duty."
US Secretary of State John Kerry described the killing, which happened a week before the Brexit referendum, as an assault on democracy.
"I join you in expressing my deep sorrow that a young parliamentarian, who obviously was a young woman with an enormous talent, has been killed in the conduct of her duties with her constituency," Mr Kerry said in Copenhagen.
"It is an assault on everybody who cares about and has faith in democracy."
