In a press conference Thursday afternoon, Collins also said a 77-year-old man was also attacked during the incident. However, details about the victim are still unknown.

Collins says police believe this was a lone incident and not part of a broader plot.

1 1:25 a.m.

Here’s more background on Cox: She was born in Batley, part of the area she represents in Parliament, and graduated from Cambridge University in 1995. Before becoming an MP, she worked as a policy analyst for Oxfam, the aid agency, and also was an adviser to Sarah Brown, the wife of former Prime Minister Gordon Brown. After her election in 2015, she was one of three-dozen Labour MPs who nominated Jeremy Corbyn for the party’s leadership. In the end, though, she voted for Liz Kendal, Corbyn’s rival for the position, and later said she regretted nominating Corbyn, who now heads the party. She also strongly supported accepting 3,000 child refugees from Syria.

11:07 a.m.

Brendan Cox, Cox’s husband who previously worked with Save the Children, tweeted this image of his wife:

10:54 a.m.

Initial eyewitness accounts of such incidents often vary from the final version, however multiple British news organizations are reporting that a witness at the scene heard Cox’s attacker shout: “Britain first.” The Guardian is reporting that local police are talking to at least one witness who heard those words being shouted. Britain First is the name of a far-right U.K. nationalist party. The party’s response:

Media desperately try to incriminate Britain First in shooting of Labour MP Jo Cox ... - https://t.co/1rENtmI7he pic.twitter.com/lGhohrf0RL — Britain First (@BritainFirst) June 16, 2016

That image on the left, which was first tweeted by the BBC, reportedly shows Cox’s attacker being apprehended.

10:33 a.m.

David Cameron, the British prime minister, says he’s canceling his visit to Gibraltar where he was scheduled to campaign for Britain to remain in the EU.

It's right that all campaigning has been stopped after the terrible attack on Jo Cox. I won't go ahead with tonight's rally in Gibraltar. — David Cameron (@David_Cameron) June 16, 2016

10:16 a.m.

Both of the main groups in the “Brexit” debate have suspended their campaigns in response to the attack on Cox.

We are suspending all campaigning for the day. Our thoughts are with Jo Cox and her family. — Stronger In (@StrongerIn) June 16, 2016

Vote Leave also said it is suspending its campaign.

In a recent monthly column, Cox had explained why she would vote to remain. An excerpt:

I know for many people that this is a tough decision, that the debate has been highly charged and the facts difficult to pin down. But I believe that the patriotic choice is to vote for Britain to remain inside the EU where we are stronger, safer and better off than we would be on our own. What’s more a vote to remain is a vote for certainty. The EU may be imperfect and definitely needs reform but risking all the current advantages of being inside Europe to take a leap in the dark doesn’t feel very patriotic to me.

And in a recent article she wrote that while immigration to the U.K—a reason often cited by backers of Brexit—was a “legitimate concern,” it wasn’t a good enough to reason to leave the EU.