A manhunt is under way to find the person behind Friday’s rush hour Tube bombing in south-west London.
Police said they were “chasing down suspects” and had hundreds of officers trawling CCTV in the wake of the District Line attack, which injured 29.
The UK terror threat has been raised to critical – the highest level – meaning an attack is expected imminently.
So-called Islamic State has said it was behind the bomb, which was detonated at 08:20 BST at Parsons Green station.
The station reopened in the early hours of Saturday.
The Met’s Assistant Commissioner Mark Rowley said it was “very routine” for IS to claim the attack “whether or not they’ve had any previous engagement with the individuals involved”.
He asked the public to remain “vigilant”, but said people should “not be alarmed”.