LONDON — British lawmaker Jo Cox, a 41-year-old mother of two, has died after she was stabbed and shot Thursday in Birstall, Northern England. Cox was declared dead at the scene by a paramedic.

A 52-year-old man has been arrested. Police are not looking for anyone else in connection with the murder, the BBC reported. A 77-year-old man was also attacked, but only suffered slight injuries.

Cafe owner Clarke Rothwell witnessed the attack. He told the BBC he heard a “loud popping noise that sounded like a balloon burst — a loud balloon.” “When I looked round there’s a man stood there in his 50s with a white baseball cap on and a jacket with a gun, an old fashioned looking gun in his hand,” he said. “He shot this lady once and then he shot her again. He fell to the floor, leant over shot her once more in the face area. Somebody tried to grab him, wrestling with him and then he wielded a knife, like a hunting knife, just started lunging at her with a knife half a dozen times. People were screaming and running from the area.”

Cox, who represented the Labour Party, was a Member of Parliament for the Batley and Spen constituency. She is understood to have held an advice session for local constituents at the nearby library in Birstall shortly before the attack.

Labour Party leader Jeremy Corbyn commented: “The whole of the Labour party and Labour family — and indeed the whole country — will be in shock at the horrific murder of Jo Cox today… Jo died doing her public duty at the heart of our democracy, listening to and representing the people she was elected to serve.”

It is unclear what the motive for the attack was, although the U.K. is in the middle of a heated campaign leading up to a referendum next week on whether to stay part of the European Union, and that has stoked nationalist and xenophobic sentiment. Police are investigating reports that the suspect shouted “Britain first.”

In a statement, the MP’s husband, Brendan Cox, said: “Today is the beginning of a new chapter in our lives. More difficult, more painful, less joyful, less full of love. I and Jo’s friends and family are going to work every moment of our lives to love and nurture our kids and to fight against the hate that killed Jo.”