A British Member of Parliament was in critical condition after being shot and stabbed in her constituency in northern England on Thursday, British police and media reports said, prompting the suspension of campaigning for next week's EU referendum.
Jo Cox, 41, a lawmaker for the opposition Labour Party and vocal supporter of Britain remaining in the European Union, was attacked as she prepared to hold a meeting with constituents in Birstall near Leeds.
West Yorkshire Police said a 52-year-old man had been arrested by armed police and that a woman in her 40s had suffered serious injuries. Police did not give any further details of the attack.
"Utterly shocked by the news of the attack on Jo Cox," Labour Party leader Jeremy Corbyn said on Twitter. "The thoughts of the whole Labour Party are with her and her family at this time."
British lawmakers are not in parliament ahead of next week's referendum on whether Britain should remain in the European Union.
The rival referendum campaign groups said they were suspending activities for the day and Prime Minister David Cameron said he would pull out of a planned rally in Gibraltar, the British territory on the southern coast of Spain.
"It's right that all campaigning has been stopped after the terrible attack on Jo Cox," he said on Twitter.
A man in his late 40s to early 50s also suffered slight injuries in the incident, police said. BBC radio reported that Cox, who is married with two children, had been taken by air ambulance to a nearby hospital.
One witness told Sky News that Cox had intervened in a scuffle between two men, one of whom had pulled a gun from a bag which had then been fired twice.
"I saw people rushing down the road towards the library. I came out with a couple of people from the restaurant ... we saw a man wearing a dirty white baseball cap with gray jacket start jostling with somebody," said Hichem Ben-Abdallah.
"All of a sudden this guy pulls a gun ... it looked like a First World War gun or makeshift gun, not the sort of gun you see normally. He fired the first shot then I ran away and then we heard the second shot."
BBC TV and other media showed a picture of the alleged suspect, a balding white man, being apprehended by police.
Media reports citing witnesses said the attacker had shouted out "Britain First", which is the name of a right-wing group that describes itself on its website as "a patriotic political party and street defense organization".
Jayda Fransen, deputy leader of Britain First, said the attack was "absolutely disgusting" and suggested that Britain first was a common slogan being used in the EU referendum campaign by those who support Brexit.
"We were as shocked to hear these reports as everyone else," Fransen told Reuters. "At the moment would point out this is hearsay, we are keen to verify the comments but we can only do that when the police provide more details."
The last attack on a British lawmaker occurred in 2010, when Labour lawmaker and former minister Stephen Timms was stabbed in the stomach at his office in east London by a 21-year-old student who was angry over his backing for the Iraq war.
In 2000, a Liberal Democrat local councillor was murdered by a man with a samurai sword at the offices in western England of lawmaker Nigel Jones who was also seriously hurt in the attack.
Cox, a Cambridge University graduate, was an aid worker before becoming Labour lawmaker for Batley and Spen in 2015. Known for her work on women's issues, she has worked with several charities.
Fellow lawmakers from several parties expressed shock and sympathy, praising Cox as a rising star of politics. Labour lawmaker Clive Betts broke down in tears while talking live on television when he said that Cox was a mother of young children as well as a politician.