Updated

British armed police have carried out a raid on a property in the central city of Birmingham, after an attacker killed four people before being fatally shot by police within Parliament's grounds.

Police refused to say if the raid was linked to the rampage in the heart of Britain's seat of power. But British media including the Press Association on Thursday quoted an unnamed witness saying that the operation was linked to the attack that also injured around 40 people.

A knife-wielding man drove an SUV into pedestrians on Westminster Bridge before crashing the vehicle into the gates of Parliament on Wednesday. He scaled the fences and later fatally stabbed a policeman before being gunned down by officers. He hasn't been identified. Three pedestrians were among the dead.