Islamic State claims responsibility for British parliament attack

The Islamic State group on Thursday claimed the deadly assault at the British parliament, as Prime Minister Theresa May identified the attacker as a British-born man known to intelligence services.

"An act of terrorism tried to silence our democracy," May told a packed House of Commons, which stood for a minute's silence in remembrance of the victims of Wednesday's strike on the symbol of Britain's democracy.

UK ATTACKS UPDATE: Seven arrested in raids in Birmingham and London linked to Westminster attack

Seven people have been arrested during raids in London, Birmingham and elsewhere linked to the terror attack in Westminster.

Acting Deputy Commissioner Mark Rowley, the Met Police's senior anti-terror officer, confirmed that two members of the public were fatally injured and PC Keith Palmer, a member of the Parliamentary and Diplomatic Protection Squad, was killed during the attack.

UPDATED: Four dead, at least 20 injured in UK parliament 'terrorist' attack

Four people were killed and at least 20 injured in London on Wednesday after a car plowed into pedestrians and an attacker stabbed a policeman close to the British parliament in what police called a "marauding terrorist attack".

The dead included the assailant and the policeman he stabbed, while the other two victims were among those hit by the car as it tore along Westminster Bridge before crashing into railings just outside parliament.

Oh goodness me! Gunshots outside UK Parliament, several injured

The UK Parliament is in lockdown after a police officer was stabbed and a dozen people mowed down on Westminster Bridge.

Commons leader David Lidington said a "police officer has been stabbed" and the "alleged assailant was shot by armed police" following a "serious incident".

There are also reports of a dozen people injured on Westminster Bridge after a car attempted to run down a number of pedestrians.