Brendan Cox, the husband of murdered Labour MP Jo Cox, said: "She would have wanted two things above all else to happen now, one that our precious children are bathed in love and two, that we all unite to fight against the hatred that killed her. Hate doesn't have a creed, race or religion, it is poisonous."

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Westminster has lost "a great star" in the death of Jo Cox, David Cameron has said.

Paying tribute to the Labour MP, the prime minister said she had "a huge heart - she was a very compassionate, caring MP" with a "great track record" in fighting for Syrian refugees.

Mr Cameron was speaking during a visit to Gibraltar where an EU referendum campaign rally was cancelled.

More on Home Secretary Theresa May's statement on Labour MP Jo Cox in which she said MPs were united "in our deep sadness at the loss of one of our brightest and most popular Westminster colleagues". 

Her thoughts and prayers, she said, were with Mrs Cox's husband Brendan and their two children, family and friends, who must be enduring "unimaginable" pain.

It was, she said, entirely appropriate that all campaigning for the referendum had been suspended.

The full facts of what happened outside Mrs Cox's constituency surgery were not yet clear, she added, and until they were she would not be commenting further.

In her statement, West Yorkshire police temporary chief constable, Dee Collins, said a man was arrested shortly after the attack on Labour MP Jo Cox.

In a news conference following the attack on Labour MP Jo Cox, Dee Collins, temporary chief constable for West Yorkshire, said: "I am now very sad to have to report that she has died as a result of her injuries."

Expressing her deepest condolences to the family and friends of Jo Cox, who had two children aged five and three, she said: 

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The Home Secretary Theresa May, giving her response to the news of the death of Labour MP Jo Cox, says the pain her family "must now be enduring is unimaginable".

"The full details of what happened outside Jo's constituency surgery are not yet clear," she says.

Expressing her "deep sadness", Mrs May says "it's entirely appropriate that all campaigning for the referendum has been suspended".

Labour MP Stephen Kinnock, who shared an office with Jo Cox, spoke of his devastation at his colleague's death.

"We just don't know what the motive is for this senseless attack," he said.

"If it's specifically connected to her role as an MP and she was targeted for that reason, there are much wider implications.

"Some people think that politicians are fair game."

Image source, PA

Continuing his statement, Jeremy Corbyn says "there will be questions to answer about how and why she died".

He added:

Labour leader Jeremy Corbyn has paid tribute to MP Jo Cox saying she was "universally liked at Westminster" and across Parliament.

Moments after West Yorkshire Police announced Mrs Cox's death, Mr Corbyn released a statement saying: “The whole of the Labour Party and Labour family - and indeed the whole country - will be in shock at the horrific murder of Jo Cox today.

“Jo had a lifelong record of public service and a deep commitment to humanity. She worked both for Oxfam and the anti-slavery charity, the Freedom Fund, before she was elected last year as MP for Batley and Spen – where she was born and grew up.

“Jo was dedicated to getting us to live up to our promises to support the developing world and strengthen human rights – and she brought those values and principles with her when she became an MP.

“Jo died doing her public duty at the heart of our democracy, listening to and representing the people she was elected to serve. It is a profoundly important cause for us all.

“Jo was universally liked at Westminster, not just by her Labour colleagues, but across Parliament."

West Yorkshire police and crime commissioner Mark Burns-Williamson says the attack on Jo Cox "is truly shocking".

Ms Collins says some weapons have been recovered. "We're in the very early stages - we're attending a number of scenes as part of this investigation," she said.

"Our working presumption is that this is a lone incident..

"The most important fact here at the moment is we have one male under arrest."

Acting chief constable Dee Collins has appealed to witnesses in Birstall to come forward following the attack on Labour MP Jo Cox.

West Yorkshire's acting chief constable Dee Collins says a full investigation is underway "to establish the motive of this attack" on Labour MP Jo Cox.

"This is a very significant investigation with large numbers of witnesses who have been spoken to at this time," she said at a news conference.

Dee Collins, West Yorkshire Police's acting chief constable, says Labour MP Jo Cox "has died as a result of her injuries"

West Yorkshire Police is expected to hold a news conference into the attack on Labour MP Jo Cox shortly.

Acting chief constable Dee Collins and West Yorkshire police and crime commissioner Mark Burns-Williamson are expected to be there.

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The Leader of the Commons Chris Grayling says the attack on Labour MP Jo Cox "is every member of parliament's nightmare".

"This is really terrible news and one's heart goes out - one's prayers for Jo and her family," the Conservative MP tells the BBC.

He says it's "terribly difficult" to see something like this happen to a new MP.

"We are exposed - we are at risk," he says, but adds: "When it happens it draws the whole political family together."

Mr Grayling says Parliament contains people of very different views. "It's 650 people representing different communities trying to do their best for them."