British Prime Minister Theresa May, who had said in her statement that Parliament "will meet as normal" today, joined MPs, peers and other Londoners in a minute's silence to show solidarity with the victims of the attack and mark the start of proceedings at House of Commons.
Four people were killed and 29 injured when a man mowed down pedestrians on a bridge and stabbed a police officer outside parliament complex before being shot dead by Scotland Yard officers.
"But let me make it clear today, as I have had cause to do before: any attempt to defeat those values through violence and terror is doomed to failure," she added.
The British PM is scheduled to make a statement to the House of Commons.
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Meanwhile, Scotland Yard have also held a vigil outside its London headquarters in memory of the officer killed by the lone attacker who ploughed down a number of pedestrians on Westminster Bridge in a car before disembarking and running up to the main entrance of Parliament where he was stopped by PC Keith Palmer - who was then stabbed to death.
"I personally was a witness to part of yesterday's events, including part of the tragic attack on Palmer. As with all police officers, I therefore had a duty to secure my evidence and produce statements yesterday evening, which I did before resuming my role leading our response to this incident," he said after the vigil.
While the identity of the attacker is yet to be revealed, it has been confirmed that the attack was inspired by "international terrorism" and that it was related to some form of "Islamic terrorism".