LONDON (AFP/REUTERS) - Sole suspect Thomas Mair appeared in court on Saturday (June 18) charged with the murder of lawmaker Jo Cox, an attack that has shocked Britain and brought a temporary halt to campaigning ahead of next week's referendum on European Union membership.

Mrs Cox was attacked with a knife and a firearm outside her constituency surgery in the village of Birstall, northern England, on Thursday. Mair, 52, who is from the Yorkshire village, was arrested close to the scene.

Mair appeared in Westminster Magistrates' Court after being charged by the police with murder, causing grievous bodily harm, and possession of a firearm and another offensive weapon.

West Yorkshire Police's Detective Superintendent Nick Wallen, who is leading the investigation, said in a brief statement that Mair had been charged with a string of crimes related to Mrs Cox's death.

Supt Wallen said Mrs Cox "was attacked and sustained serious injuries from both a firearm and a knife and despite assistance from passers-by, the ambulance service and police officers who were quickly on the scene, she sadly died of her injuries".

Supt Wallen said the suspect was quickly apprehended thanks to help from the public. He said the police, working with the North East Counter Terrorism Unit, was pursuing inquiries into media reports of"the suspect being linked to right wing extremism" and "the suspect's link to mental health services".

"Based on information available at this time, this appears to be an isolated, but targeted attack upon Jo - there is also no indication at this stage that anyone else was involved in the attack. However we will be investigating how the suspect came to be in possession of an unlawfully held firearm," Supt Wallen added.

He said, however, that the police were working with the Palace of Westminster and the Home Office to review security arrangements for members of Parliament.

Mrs Cox's murder has sent shockwaves through British politics and drawn messages of condolence from around the world, with United States President Barack Obama condemning the "heinous" attack.

Campaigning ahead of next Thursday's closely-contested referendum on Britain's membership of the European Union remains suspended on Saturday as a mark of respect.

Prime Minister David Cameron and opposition Labour leader Jeremy Corbyn laid bouquets at a massive floral tribute to Cox in Birstall on Friday.

"Where we see hatred, where we find division, where we see intolerance, we must drive it out of our politics and out of our public life and out of our communities," Mr Cameron said. "Today our nation is rightly shocked."

The White House said Mr Obama offered condolences to Mrs Cox's widower and praised her "selfless service".

Mr Obama called Mr Brendan Cox while travelling on the Air Force One presidential plane. "President Obama offered his sincere condolences on behalf of the American people to Mr Cox and his two young children, as well as to her friends, colleagues and constituents," the White House statement said.

"The President noted that the world is a better place because of her selfless service to others, and that there can be no justification for this heinous crime, which robbed a family, a community and a nation of a dedicated wife, mother and public servant."

Mrs Cox, a former aid worker who was campaigning for Britain to stay in the EU and also spoke out for Syrian refugees, was killed just a few kilometres from where she was born.

Eyewitness Hichem Ben Abdallah, 56, told AFP he heard two shots and saw her on the ground. "Her face was full of blood," said Mr Abdallah, who campaigned alongside the Labour politician before she was elected to Parliament for the first time last year.

A fund created in Mrs Cox's memory by her friends and family has raised more than £200,000 so far for charities close to her heart.

The money will support the Royal Voluntary Service which helps combat loneliness in her constituency; the Hope Not Hate anti-extremism group and the White Helmets volunteer search and rescue workers in Syria.

At a vigil in London's Parliament Square on Friday evening, hundreds of people gathered to lay flowers and pay their respects, holding a minute's silence.

Former Labour leader Ed Miliband joined former deputy leader Harriet Harman and Labour MP Wes Streeting in paying tribute to Mrs Cox.

"Her legacy of giving a voice to the voiceless, particularly those caught up in war and in conflict, her legacy of standing up against oppression wherever she found it, and her legacy of preaching the values of unity and not division," said Mr Miliband. "Jo Cox only loved, she never hated."

Mr Streeting added: "What we can all do here today is pledge ourselves in any way that we can to make the world that Jo was fighting for.

"A world of humanity, of decency, of compassion, of solidarity, of human rights, and social justice, simple kindness."

Mrs Cox is the first female British MP to be murdered. The last British lawmaker killed in office was Ian Gow, who was assassinated by Irish Republican Army paramilitaries in a car bomb attack in 1990.

Mrs Cox lived with her husband and their two children, aged three and five, on a houseboat moored on the River Thames in London, close to the city's iconic Tower Bridge.

Mourners laid flowers on the roof of the converted barge along with pictures of the slain MP.