Jo Cox, who was the Labour MP for Batley and Soen, was shot three times by a gunman carrying a “handmade weapon” as she arrived at her offices near Leeds.
He then stabbed her repeatedly as she lat bleeding on the ground.
According to eyewitness accounts, her attacker had screamed “Britain First” as he carried out the atrocious crime.
Describing the gunman’s actions, witness Clarke Rothwell told BBC News: “He shot this lady once, then he shot her again and she fell to the floor.
“[He] went over, shot her once more in the face area, somebody tried grabbing, wrestling with him, then he was wielding a knife, a hunting knife.”
The 41-year-old politician, who has been campaigning tirelessly for Britain to remain in the EU, was rushed to hospital after the shocking attack.
Tragically, however, she did not survive her catastrophic injuries.
Jeremy Corbyn, the leader of the Labour Party, gave the following statement to the press:
“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 Cox 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 Cox 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.”
Prime Minister David Cameron also expressed his condolences on Twitter, writing: “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.”
He added that all campaigning will be temporarily stopped as a mark of respect to the fallen MP.
Police have arrested a 52-year-old man in connection with the shocking incident.
Jo Cox was an invaluable member of the Labour Party, and was elected to the seat of Batley and Spen at the last general election in 2015.
She had been educated at Heckmondwike Grammar School, going on to study at Cambridge University, from which she graduated in 1995.
Speaking about her education in a recent interview with the Yorkshire Post, she said: “I never really grew up being political or Labour. It kind of came at Cambridge where it was just a realisation that where you were born mattered, that how you spoke mattered … who you knew mattered.
“I didn’t really speak right or knew the right people. I spent the summers packing toothpaste at a factory working where my dad worked and everyone else had gone on a gap year.
“To be honest my experience at Cambridge really knocked me for about five years.”
Before going on to become a Labour MP, she worked tirelessly for Oxfam as their head of policy.
Mark Goldring, Oxfam's chief executive, told BBC News: "Oxfam is deeply shocked to hear the news.
“Our thoughts and sympathies are with Jo and her family at this difficult time."
She was frequently described as the “kindest and most passionate” MPs, campaigning tirelessly for international causes, and frequently working with schools to better educate young children about good citizenship.
The mother-of-two was at the forefront of the campaign to keep Britain in the EU, and stirelessly worked to persuade the government to accept more child refugees from Syria.
She argued in a piece for The Observer: “There is nothing ethical about standing to one side when civilians are being murdered and maimed.
“There was no excuse in Bosnia, nor Rwanda and there isn’t now.”
Jo Cox also, in yet another demonstration of her benevolence, spent her time advising the NSPCC and Save the Children on their UK activities.
She also worked to help the older people in her constituency, earning praise from the Alzheimer's Society.
It is clear that the country has lost a truly remarkable woman, whose passion and dedication saw her fight for the causes she truly believed in.
Our hearts go out to all her friends and loved ones - and particularly to her husband, Brendan Cox, and their son and daughter.