Parsons Green station has re-opened after a bomb was detonated on a London Underground train, injuring 29 people.
The improvised explosive device sent a fireball through a packed train carriage during Friday morning rush hour .
Britain is currently on the highest terror alert, meaning another attack is expected imminently, and a manhunt is under way for the "suspects".
Transport for London announced that the south-west London station had reopened at 1.30am on Saturday, more than 17 hours after the incident.
On Friday night, British Prime Minister Theresa May raised the terror threat level to critical, as Assistant Commissioner Mark Rowley suggested there may have been more than one person involved.
He said police were "chasing down suspects".
The Islamic State (IS) terror group has claimed responsibility for the attack through its Amaq news agency, according to the US-based Site Intelligence.
In a statement outside Scotland Yard, Mr Rowley, the UK's most senior anti-terror police officer, said: "Somebody has planted an improvised explosive device on the Tube - we have to be open-minded at this stage about him and about potential associates."
He said detectives were only aware of one device and refused to be drawn on details of the suspects because of the "covert" nature of the operation.
Mr Rowley said detectives have spoken to tens of witnesses, taken a large number of calls to the anti-terror hotline from members of the public, and have so far received 77 images and videos taken at the scene.
He added: "Meanwhile, the improvised explosive device on the train, the remnants of it, have now been made safe and they've been taken away for specialist examination by forensic scientists.
"So whilst we chase down the suspects, as the public would expect, we are strengthening our policing resources on the streets of London and across the country whilst continuing the investigation.
"I have asked Government ministers earlier on for permission to use members of the military to free up extra police resources.
"What that gives me and my team is an extra thousand armed police officers, largely from Civil Nuclear Constabulary and Ministry of Defence police.
"We are working through all of those lines of inquiry, we are making really good progress on that investigation.
"I've had a very detailed briefing on the device, it's components and how it works, I think to put that information out publicly at the moment would be inappropriate given it's part of the investigation."
It is the second time this year that the threat assessment - made by the Joint Terrorism Analysis Centre - has been raised to the highest level.
It was placed at critical in May in the wake of the Manchester bombing, before being lowered back to severe four days later.
Before this year the most serious category had only been reached on two other occasions since it was first publicly disclosed in August 2006.
As Britain faced up to another terrorist incident, following four attacks already this year:
:: Images emerged on social media appearing to show wires protruding from a flaming bucket inside a plastic Lidl carrier bag on the floor of a carriage;
:: Reports suggested the device had a timer;
:: A total of 29 patients needed hospital treatment, with a number of those hurt suffering from burns;
:: Scotland Yard and the Prime Minister rebuked US President Donald Trump over his claim the Parsons Green Tube bomber was "in the sights" of Scotland Yard.