Jo Cox, a member of the British parliament, died after being shot in northern England, UK police have said.
West Yorkshire Police said on Thursday a 52-year-old man had been arrested following the incident, which prompted the suspension of campaigning for next week's referendum on the country's EU membership.
The attack took place in Birstall, near the city of Leeds. It happened outside the library, where she regularly held meetings with her constituents.
Police said a 77-year-old man was also assaulted in the incident and suffered injuries that were not life-threatening.
One witness told the Press Association that Cox had intervened in a scuffle between two men, one of whom pulled a gun from a bag and then fired twice.
Officers said weapons, including a firearm, had been recovered from the scene.
"This was a localised incident, albeit one which has a wider impact," West Yorkshire Police and Crime Commissioner Mark Burns-Williamson told reporters.
