A vigil is to be held to remember the victims of the attack in Westminster, the Mayor of London has announced.

Sadiq Khan has encouraged Londoners and visitors to attend the event, which will take place today (Thursday) at 6pm in Trafalgar Square, to “remember the victims of yesterday’s attack and stand against terrorism”.

Two members of the public and a police officer have died and dozens more were injured after the attacker mounted the pavement on Westminster Bridge and ploughed his car into pedestrians, before fatally stabbing a police officer outside Parliament.

In a statement released on Thursday morning, the Mayor’s Office invited people to “come together in solidarity” with the victims and their families, and urged that London would “stand together in the face of those who seek to harm us and destroy our way of life.

“The Mayor invites all Londoners – and everyone visiting our city - to come together in solidarity to remember those who have lost their lives, to express sympathy with their families and loved ones and to show the world that we are more committed than ever to the values that we hold dear – that we remain united and open,” the statement read.

Shortly after the attacks, Mr Khan released a video message in which he said Londoners would "never be cowed by terrorism".

"London is the greatest city in the world, and we stand together in the face of those who seek to harm us and our way of life," the Mayor said.

"We always have and we always will.

"There will be additional armed and unarmed police officers on our streets from tonight in order to keep Londoners, and all those visiting our city, safe.

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

"I want to reassure all Londoners, and all our visitors, not to be alarmed."

Communities around the world have shown solidarity with those affected by Wednesday's Westminster terror attack through a series of poignant gestures.

As midnight fell in France on Thursday night, the Eiffel Tower switched its lights off to honour those killed in the London massacre.