Brendan Cox has urged Britain not to let itself be divided by the Westminster attack, saying the assailant no more represents British Muslims than his wife’s murderer represented the people of Yorkshire.

Jo Cox, a Labour MP, died after being shot and stabbed outside her constituency surgery in Birstall, West Yorkshire on 16 June by far-right extremist Thomas Mair.

Mr Cox said it was important to remember the victims, and not the assailant, of yesterday's terror attack outside Parliament and on Westminster Bridge that left four dead.

"What the terrorist would like to happen is for us to fall apart and start blaming groups of people, to say that in some way this is Muslim or Islam as a whole," he told Radio 4's Today programme.

"We have to remember that the person who did this is no more representative of British Muslims than the person who killed Jo is representative of people that are from Yorkshire."

"I’m going to do whatever I can to remember the names of the victims like PC Palmer and not the name of the person who did this, partly driven by the desire for notoriety," he said.

Seven people remain in hospital in a critical condition after the incident, in which a man drove a car along a pavement and stabbed a policeman before being shot dead by police.

The officer, who died from his injuries, was named as 48-year-old Keith Palmer. A woman in her 40s and a man in his 50s were also killed in the attack.

“The first thing we need to do is to remember that this is a story about people who didn’t come home yesterday, and the impact that will have on their families, the thousands of lives that will be touched by the individual tragedies,” said Mr Cox.

Tributes to murdered MP Jo Cox (Garry Knight)

“What helped me in the weeks after [Ms Cox’s death] was that sense of public support, those thousand acts of kindness – the sense the person you lost meant something not just to you, but to others.”

PC Palmer, a husband and father who had served in the Metropolitan Police for 15 years, was outside Parliament when a man armed with two knives entered the gates and stabbed him.

Mark Rowley, the Met's top anti-terror officer, said PC Palmer was "someone who left for work today expecting to return home at the end of his shift, and he had every right to expect that would happen."

In pictures: Westminster attack Show all 9 1 /9 In pictures: Westminster attack In pictures: Westminster attack An air ambulance lands after gunfire sounds were heard close to the Palace of Westminster in London PA wire In pictures: Westminster attack MPs wait until the situation is under control in Westminster. 'The alleged assailant was shot by armed police,' David Lidington, leader of the House of Commons, told the house. BBC News In pictures: Westminster attack Crowds gather in Westminster after shooting incident, which police are treating as terror attack BBC News In pictures: Westminster attack Police were also called to an incident on Westminster Bridge nearby AP In pictures: Westminster attack Early reports indicate the car, which mounted the pavement on Westminster Bridge and mowed into around a dozen people, was the same vehicle which then rammed into the railings of the Palace of Westminster, just around the corner Reuters In pictures: Westminster attack Security sources described the suspected assailant as a middle-aged Asian man, who is understood to have left the car before attacking a police officer with a seven-to-eight inch knife PA wire In pictures: Westminster attack Police have asked people to avoid the immediate area to allow emergency services to deal with the ongoing incident AP In pictures: Westminster attack One woman has died and a number of others, including the police officer, have been hurt, according to a junior doctor at St Thomas' Hospital Reuters In pictures: Westminster attack At least three gun shots were heard by those inside Westminster, and proceedings in the House of Commons have been suspended AP

Speaking outside Scotland Yard, acting deputy commissioner Rowley said: "Today in Westminster we saw tragic events unfold and our thoughts are with those who lost loved ones, those who were injured and all those affected by this attack".

A further three police officers were among the injured, two of whom were in a serious condition, he added.

The attack began at around 2.40pm and proceedings in the House of Commons were immediately suspended. Deputy speaker David Lidington announced to the House that a police officer had been stabbed and the “alleged assailant shot by armed police”.

Images have emerged of a man dressed in black, believed to be the suspect, being treated on a stretcher within Parliament grounds. A knife could be seen lying on the ground nearby.

Seven people have been arrested in connection with the attack after police searched six addresses, said Mr Rowley.

Defence Secretary Sir Michael Fallon told the Today programme the “working assumption” was the attack was linked to “Islamic terrorism in some form”.

Aysha Frade, 43, died of her injuries after the attacker ploughed his car into pedestrians on Westminster Bridge.

Spanish media said Ms Frade had two daughters aged eight and 11 and worked at the nearby DLD College London.

Westminster attack: What we know so far

Mr Rowley said 29 people had been treated in hospital with seven people in a critical condition.

“We must not allow terrorists to create discord, distrust and fear," he said. “The police stand with all communities, later today a meeting of faith leaders will be held here at New Scotland Yard.

“Whilst our work to investigate and understand what happened yesterday continues with vigour, we must also reflect.