AN explosion on a London Underground train which sent passengers and those in the vicinity fleeing in fear is being treated as a terrorist incident by police.

Here is what we know so far:

  • Emergency services including police, fire and ambulance were called to the scene at around 8.20am after an improvised explosive device detonated in a carriage.
  • The District line train, bound for central London, had just stopped at Parsons Green station in the west of the city when the explosion happened.
  • Twenty-two people have been injured, most of whom police said suffered "flash burns". Casualties were taken to trusts across London including Imperial, Chelsea and Westminster and Guy's and St Thomas'. St Mary's Hospital in Paddington declared a major incident but has since been stood down.
  • Around two hours after the explosion, the Metropolitan Police confirmed they were treating it as a terrorist incident.
  • London Mayor Sadiq Khan told LBC radio "there is a manhunt under way as we speak". There have been no arrests.
  • US President Donald Trump denounced the attack by "sick and demented people who were in the sights of Scotland Yard". The Met declined to comment.
  • Witnesses said they saw a white "builder's bucket" in a supermarket bag, and pictures online appeared to show a flaming bucket with wires protruding from it inside a plastic carrier bag on the floor of a carriage. Reports suggested the device had a timer.
  • People reported seeing a "fireball" and a "wall of flame" in the train and people "covered in blood".
  • The public has been warned to expect an "enhanced police presence", particularly across the transport system, on Friday.