A British lawmaker was shot to death while meeting with constituents Thursday in an attack that halted campaigning over whether the U.K. should leave the European Union.
Police said they arrested a 52-year-old man in the attack on Jo Cox, but did not know of a motive for the killing. The attack came a week before British voters were scheduled to decide whether to leave the EU. Cox, a 41-year-old member of the opposition Labour Party, had been campaigning to keep the U.K. in the European Union.
Cox was meeting voters in her West Yorkshire, northern England, constituency when she was attacked.
Authorities said in a news conference that they are conducting a "very significant investigation," appealing to witnesses for more information.
A representative from the local police said they are "not able to say at present" exactly what unfolded in the attack or a potential motive, but that there are indications this was a lone incident. Weapons, including a firearm, were recovered, police said.
The Vote Leave and Britain Stronger in Europe campaigns suspended activity after the attack on Cox, who was elected to the House of Commons only last year.
Prime Minister David Cameron called the attack "absolutely tragic and dreadful news."
Labour leader Jeremy Corbyn said he was "utterly shocked by the news of the attack on Jo Cox. The thoughts of the whole Labour Party are with her and her family at this time."
According to media reports, which have not been verified by NBC News, the assailant shouted "Britain First" as he attacked Cox — a possible reference to arguments over whether the U.K. should remain as part of the EU.
ITV News reports that all campaigning concerning the referendum has been suspended for the rest of the day following the incident in Yorkshire.
Britain's Press Association news agency quoted eyewitness Hithem Ben Abdallah as saying Cox got involved in a scuffle between two men in Birstall, 200 miles (320 kilometers) north of London.
Abdallah said one of the men was fighting with Cox and then a gun went off twice and "she fell between two cars and I came and saw her bleeding on the floor."
Shopkeeper Sanjeev Kumar told the BBC said he saw a woman lying on the ground "bleeding from the mouth and nose," with two women trying to help her.
After around 15 minutes, the shop owner said emergency services arrived and tended to her with a drip.
— The Associated Press contributed to this report.
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