Terrified passengers described seeing victims covered in blood as people scrabbled to evacuate after an explosion on a London Underground train.
Commuter Peter Crowley suffered burns to his head after flames swept through a packed carriage at Parsons Green station on Friday morning.
"A fireball above my head has come and singed all my hair," he told BBC News.
"I've got burn marks on the top of my head and everyone just ran off the train - it was quite scary."
Sylvain Pennec, a software developer from Southfields, near Wimbledon, said fire filled the carriage.
"I heard a boom and when I looked there were flames all around," he said.
"People started to run but we were lucky to be stopping at Parsons Green as the door started to open."
He described the scene of panic as commuters struggled to escape the carriage, "collapsing and pushing" each other.
Mr Pennec stayed behind to take a closer look at what he believed was the source of the explosion.
"It looked like a bucket of mayonnaise," he said.
"I'm not sure if it was a chemical reaction or something else, but it looked home-made. I'm not an expert though."
Media technology consultant Richard Aylmer-Hall, 53, was sitting on the service bound for central London when panic unfolded at around 8.20am.
He said he saw several people injured, having apparently been trampled as they tried to escape.
He told the Press Association: "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.
"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."
Aaron Butterfield, a production manager, said he saw people "crawling over one another" in panic as they tried to get out of the station.
He added: "People weren't even running, they were literally crawling over one another and just fleeing I guess.
"It's been really frightening and very confusing especially as no-one really knows what's going on."
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," he told BBC 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."
BBC News presenter Sophie Raworth, who was at the scene, said she saw a woman on a stretcher with burns to her face and legs.
She added: "Her legs are wrapped up and she has burns.
"She had burns to her face - she's conscious, she was taking oxygen and pain relief as well.
"She seemed to have burns all over her body from top to toe."