Terrified passengers fled Parson's Green station following reports of an explosion on board a packed District Line train .
Eyewitnesses have described the aftermaths of an explosion, which is reported to have left some people with "facial burns".
The incident happened around 8.20am train on the morning of Friday September 15 and at 10.09am, The Metropolitan Police confirmed it was treating it as a terror incident.
Media technology consultant Richard Aylmer-Hall, 53, was sitting on the District Line train bound for central London when panic unfolded.
He said he saw several people injured, having apparently been trampled as they tried to escape.
He said: "I was blissfully reading my paper and listening to a podcast and suddenly the whole world charged past me down the platform, down the Tube."
He added: "I was on the Tube, we had just stopped at Parsons Green, I was on my way up from Wimbledon towards Paddington and suddenly there was panic, lots of people shouting, screaming, lots of screaming.
"There was a woman on the platform who said she had seen a bag, a flash and a bang, so obviously something had gone off.
He added: "It was an absolutely packed, rush-hour District Line train from Wimbledon to Edgware Road.
"I saw crying women, there was lots of shouting and screaming, there was a bit of a crush on the stairs going down to the streets.
"Some people got pushed over and trampled on, I saw two women being treated by ambulance crews.
"Since then, every emergency vehicle in London has gone past me, fire engines, ambulances, every type of police vehicle."
Eyewitnesses tweeted pictures on social media of armed police and London Fire Brigade officers on the tracks at Parson's Green.
One man who arrived at the station in the aftermath of the incident said: "I was walking towards the station and suddenly everyone came running down the stairs and out of the door.
"Lots of people shocked and screaming and saying there had been an explosion and people were saying there had been a wall of flame coming down the tube carriage, I turned round and came back from the station with all of them.
"A wall of flame coming down the carriage after a bang.
One woman standing on the platform as passengers left the Tube carriage in footage of the aftermath was heard saying: "We could see it on the far end of the train, I don't know what it was - it looked like a fireball.
"Something went off - I could see it.
"I saw the thing and everybody panicked and got crushed."
Commuter Robyn Frost was arriving at the station when she saw people trying to escape.
She said: "I walked into the station, there was blood on the floor and people running down the stairs screaming 'get out'.
"People were coming out of the station covered in blood."
Scotland Yard said: "Police were called at approximately 08:20hrs on Friday, 15 September to Parsons Green Underground Station following reports of an incident on a Tube train.
"Officers from the Metropolitan Police Service and British Transport Police are in attendance along with the London Fire Brigade and London Ambulance Service.
"We would advise people to avoid the area."
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