British counter-terror police searched three properties in the Midlands late Tuesday after a car crashed into security barriers outside the Houses of Parliament in central London, injuring at least 3 persons.
British Prime Minister Theresa May called it an "appalling incident".
Armed police swarmed Westminster at about 7.40 a.m. (BST) on Tuesday and a 29-year-old British man was arrested on suspicion of terror offences.
The focus has since shifted northward with three police forces now involved in raids in Birmingham and Nottingham.
Images posted to social media showed a man, wearing a black puffer jacket and surrounded by officers, being led away in handcuffs from a silver-colored Ford Fiesta, which police later said was driven to London from Birmingham overnight.
The man is being held in custody at a south London police station but is not co-operating with officers, counter-terrorism head Neil Basu said.
