Floral tributes and candles are placed by a picture of slain Labour MP Jo Cox at a vigil in Parliament square in London on Thursday. Photo: IC

World leaders on Friday sent condolences to the family of a British member of Parliament who was murdered in the street in northern England on Thursday as local people to remember the pro-EU lawmaker.

US Secretary of State John Kerry was quoted by Reuters as saying that "It is an assault on everybody who cares about and has faith in democracy."

German Chancellor Angela Merkel was quoted by Reuters as saying that "the incident is terrible, dramatic ... I don't want to connect this with the vote on Great Britain staying in the EU."

Leaders from other countries, including France, Denmark, and the Netherlands   also sent their condolences.

Jo Cox, a 41-year-old lawmaker of the opposition Labour Party and vocal supporter of Britain remaining in the EU was gunned down in Birstall near Leeds on her way to hold a meeting with constituents.

Eyewitnesses cited by British media said she had been shot two or three times before being stabbed repeatedly by a man who subsequently walked away.

West Yorkshire Police was quoted by Reuters as saying that a 52-year-old man, named in the media as Thomas Mair, was arrested and weapons including a firearm recovered.

The motive for the attack was not immediately known, according to British media.

After graduating from Cambridge University, Cox worked for years in the charity sector. She is best known for her campaigning in favor of refugee rights and for Britain staying in the EU.

Brendan Cox, her husband, was quoted by British media as saying that "She would have wanted two things above all else to happen now, one that our precious children are bathed in love and two, that we all unite to fight against the hatred that killed her."

Labour leader Jeremy Corbyn said in a statement that the whole country would be in shock at the "horrific murder."

Residents from Birstall sent dozens of floral tributes at the foot of a statue in the center of Birstall. Vigils were held in Parliament Square, London, as people gathered to pay tribute to the slain politician. 

Cox's killing comes as the momentous public referendum on voting to stay or leave the EU coming in June 23.

Chancellor George Osborne said in a statement on Thursday that "the referendum is a great exercise in democracy. But the campaign has been suspended, on both sides, out of respect for Jo and her family - and for that democracy that she served."

Cameron said in a statement that "It is right that we are suspending campaigning activity in this referendum, and everyone's thoughts will be with Jo's family and her constituents at this terrible time."

Cameron who canceled a scheduled "Stronger In" pro-EU rally in Gibraltar on Thursday and went to Birstall to join an event with Jeremy Corbyn, Mirror reported on Friday.

As a supporter of Britain voting to remain in the EU, Cox's tragic death may boost the pro-EU campaign, analysts said.

"It may change the psychology of the campaign. Those who are pro-EU may benefit from this tragic event ... it could boost their chances," Fariborz Moshirian, director of the Institute of Global Finance at the University of New South Wales, was quoted by CNBC.

The pro-EU "Remain" campaign has fallen behind the "Leave" camp in pre-referendum polls, British media reported.