“Police officers have evacuated and are searching a residential address in Sunbury, Surrey,” a statement said.

Authorities declined to release further details of the man because of “strong investigative reasons”.

The improvised explosive device failed to detonate fully, according to media reports, but the blast inflicted flash burns on passengers while others fled in panic.

UK raises threat level to critical after London train blast

“This arrest will lead to more activity from our officers,” police said, adding that the teenager was being held under anti-terror legislation.

In a statement, antiterrorism chief Mark Rowley said officers were “chasing down suspects”.

“Somebody has planted this improvised explosive device on the Tube. We have to be open-minded at this stage about him and potential associates,” he said.

Friday’s incident – claimed by Islamic State (IS) – led to the national threat level being raised to critical, meaning another attack could be imminent. The last time the warning was used was after a deadly suicide bombing at Manchester Arena, also claimed by IS, in May.

In a statement, IS said a “detachment” had carried out the latest London attack.

Prime Minister Theresa May condemned Friday’s attack as “cowardly”, and said troops would take on responsibility for guarding key sites, including nuclear facilities, to free up police.

An additional 1,000 were deployed, with more police added to the transport network and streets across Britain.

‘Fireball flew down carriage’: terror blast on London train leaves passengers burnt and trampled

May said the home-made explosive device was “clearly intended to cause significant harm”.

The remnants of the bomb, which looked to be in a bucket used by builders with cables coming from it, were examined by forensic scientists but no further details were released. British media reported that it had a timer that failed to properly detonate.

Otso Iho, a senior analyst at Jane’s Terrorism and Insurgency Centre, said the attack showed a “continued high intent but low capability” in the terrorism threat in Britain.

Hans Michels, a professor of chemical engineering at Imperial College, said the flash flame “suggests that the explosion was only partly successful”.

Victims were treated in hospital although health authorities said none were in a life-threatening condition. Three remained in care on Saturday morning.

Witnesses described the chaos after Friday’s explosion.

Charlie Craven said he heard a “massive bang” and “an orange sort of fireball encompassing the whole Tube coming towards you”.

Lauren Hubbard described it as “a wall of fire”.

Twitter user @Rrigs posted pictures of a white bucket smouldering on the train and described how a “fireball flew down carriage and we just jumped out open door”.

Louis Hather, 21, had been travelling to work and was three carriages down from the explosion.

“I could smell the burning. Like when you burn plastic,” he said.

He was trampled on as passengers stampeded out of the station and his leg was badly cut and bruised.

Four previous attacks in London and Manchester this year have claimed the lives of 35 people. Three of those attacks involved a vehicle ploughing into pedestrians.