Many injured by explosion on London Tube Parsons Green terror attack.

An explosion on a London Tube train that sparked panic among passengers is being treated as a terrorist incident, Scotland Yard has said.

Passengers, including children, fled the District Line train after an Improvised Explosive Device (IED) detonated at Parsons Green Station.

Eyewitnesses described a “fireball” and a “wall of flame” through the packed London Underground train after the blast, which happened at around 8.20am on Friday, as one commuter described how his hair was left singed by the blast.

In a statement, Metropolitan Police Assistant Commissioner Mark Rowley said the blast was caused by an Improvised Explosive Device (IED).

An investigation is now underway led by the Metropolitan Police’s Counter Terrorism Command, he said, with hundreds of detectives carrying out enquiries including examining CCTV, forensic work and speaking to eyewitnesses.

London Ambulance Service said 18 people were taken to hospital after the explosion and ACC Rowley said he understood most of those to be “flash burns”.

Chris Wildish, who was on the train, said he saw a “device” in the last carriage.

“It was a white bucket, a builder’s bucket, in a white Aldi bag or Lidl bag,” he told 5 live.

“Flames were still coming out of it when I saw it and had a lot of wires hanging out of it – I can only assume it was done on purpose.

“It was standing against the door of the rear-most carriage.”

Prime Minister Theresa May will chair a meeting of the Government’s Cobra emergencies committee this afternoon to discuss the incident at Parsons Green.

She said: “My thoughts are with those injured at Parsons Green and the emergency services who, once again, are responding swiftly and bravely to a suspected terrorist incident.”

Foreign Secretary Boris Johnson appealed for calm, saying: “It really is important not to speculate at the moment.

“Obviously, everybody should keep calm and go about their lives in a normal way, as normal as they possibly can.

“As far as I understand it, the British Transport Police and TfL are on it and they will be updating their websites as and when we have more information.”