Jo Cox, a Labour party member of the British Parliament, is dead after being shot and stabbed multiple times during a visit to her constituency in West Yorkshire.
The Guardian reported witnesses seeing Cox involved in an altercation between two men before being airlifted by helicopter to a nearby hospital. Police are investigating whether the suspect, named locally as Tommy Mair, shouted "Britain First" before firing at the politician. Another man was reportedly injured in the attack.
Britain First is a nationalist group that calls itself a "patriotic political party and street defense organization."
U.K. Prime Minister and head of the Conservative Party David Cameron responded to the news on Twitter, calling Cox a "committed and caring MP."
Police arrested a 52-year-old man in the area who might be linked to the attack, CNN reported. "At 12:53 today, police were called 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 police statement said.
It isn't the first time someone from Cox's party has been attacked: In 2010, Labour MP Stephen Timms was stabbed while in London.
Labour party leader Jeremy Corbyn expressed his sadness for Cox on Twitter Thursday.
"Utterly shocked by the news of the attack on Jo Cox," Corbyn wrote. "The thoughts of the whole Labour Party are with her and her family at this time."
Cox was voted to represent Batley and Spen in Yorkshire in May 2015. She supported the U.K. remaining in the European Union — a referendum going up for a vote next week, CNN reported. Her last tweet from Friday stated, "Immigration is a legitimate concern, but it's not a good reason to leave the EU."
"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," her husband said in a statement. "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 ave a creed, race or religion, it is poisonous."