The EU referendum campaigns have fallen silent in reaction to the death Labour MP Jo Cox, who was killed on 16 June after being shot and stabbed in her West Yorkshire seat of Batley and Spen. Cox, 41, was attacked following a constituency surgery at Birstall Library.
A 52-year-old suspect, named as Tommy Mair, has been arrested by West Yorkshire Police. Eye-witnesses to the incident claimed that he shouted "Britain first". The political group Britain First has denied to IBTimes UK any connection between the organisation and the suspect.
Britain Stronger in Europe, Vote Leave and other EU referendum groups have suspended campaigning for at least a day and there is currently no indication when they will restart, while Labour leader Jeremy Corbyn has led tributes to Cox.
"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," he said.
"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.
"In the coming days, there will be questions to answer about how and why she died. But for now all our thoughts are with Jo's husband Brendan and their two young children. They will grow up without their mum, but can be immensely proud of what she did, what she achieved and what she stood for.
"We send them our deepest condolences. We have lost a much loved colleague, a real talent and a dedicated campaigner for social justice and peace. But they have lost a wife and a mother, and our hearts go out to them."
Cox's widower, Brendan, also released a statement after her death was announced. "Jo believed in a better world and she fought for it every day of her life with an energy, and a zest for life that would exhaust most people," he 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. Jo would have no regrets about her life, she lived every day of it to the full."
The couple and their two young children had taken part in a pro-Remain counter demonstration on the River Thames on 15 June, as Fisherman for Leave flotilla sailed towards the Houses of Parliament.
The Brexit campaigners included Ukip leader Nigel Farage, whose party also cancelled all events for 17 June. Cox's death came with a week to go before the 23 June referendum, with recent opinion polls registering a rise in support for a Leave vote.
John Bercow, the speaker of the House of Commons, said: "I am absolutely devastated to learn the news about Jo Cox. Jo was an outstanding Member of Parliament and a wonderful, kind, caring person who was liked and respected in all parts of the House. My thoughts and prayers are with her family at this harrowing time."