LONDON • Commuters and witnesses described scenes of terror and panic after a rush-hour explosion sent a "fireball" through a subway train in west London.

Ms Emma Stevie, 27, was on the train when the blast happened at the Parsons Green station and was then caught in a "stampede" and crush on the station steps.

"I heard lots of screams and people saying 'run, run'," Ms Stevie told BBC News.

"We got out and then there was a human stampede, down the stairs.

"There were people lying underneath getting crushed... I kept thinking, 'I'll be ok, I'll be ok'."

Mr Sylvain Pennec, a software developer, said he had been about 10 metres from the explosion and fire filled carriage.

"I heard a boom, and when I looked, there were flames all around," he said, BBC reported.

He saw what he believed was the source of the explosion.

"It looked like a bucket of mayonnaise," he said.

Among the commuters were many schoolchildren and mothers taking their children to school.

Mr Luke O'Connor told BBC: "There (were) lots of school kids... mothers doing the school run.

"I was sitting next to a girl who was just doing her spellings, people just getting ready for the day.

"You never expect it to happen."

Commuter Eduardo Moreira said he thought most of the injuries had been caused by people "panicking and running away".

"Even in my carriage, one guy just yelled to stop. They were passing over this lady. She was being trampled on," he told BBC.

"There was high panic. The problem was people didn't know what was happening."

Ms Rachel Green, 18, who works in a coffee shop next to Parsons Green, and her colleagues helped people coming out of the station.

"At first there were 20, and then there were over 100 - women coming out without shoes, battered and bruised, and they'd left their handbags behind," she told BBC.

"There was talk of a fire - two people came into the shop with their clothes burnt off, who said they saw a fire coming towards them.

"There were mothers with babies, it was the school rush time. I'm really shocked - this is a quiet family friendly area".