A British lawmaker from the opposition Labour Party has been shot and injured in her constituency in northern England, media reported on Thursday.

A British lawmaker from the opposition Labour Party has been shot and injured in her constituency in northern England, media reported on Thursday.

Jo Cox, 41, a mother of two, was left bleeding on the pavement after the incident in Birstall in Yorkshire, the Press Association cited an eyewitness as saying.

"At 12.53 today, police were called to a report of an incident on Market Street, Birstall, where a woman in her 40s had suffered serious injuries and is in a critical condition," the police said in a statement.

"A man in his late 40s to early 50s nearby also suffered slight injuries. Armed officers attended and a 52-year-old man was arrested in the area," it said.

Channel 4 News quoted Cox's office as saying that the pro-EU MP had been shot and stabbed. The BBC said she was flown by air ambulance to Leeds.

Contacted by AFP, her offices in London and Yorkshire could not immediately be reached.

"Very concerned about reports Jo Cox has been injured. Our thoughts and prayers are with Jo and her family," Prime Minister David Cameron tweeted.

The attack took place near the town's library where she regularly held meetings with constituents.

Cox was elected at the last general election in 2015.

"Utterly awful news about an attack on a superb and wonderful colleague Jo Cox -- hoping and praying for her and her family right now," fellow Labour MP Chuka Umunna said.