Commuters were trapped in the tunnel for up to two hours

Many of those caught up in the incident said that at first, they thought they were the victims of a terrorist attack.

Speaking to the BBC, Paul Orrock, 32, said he was in the third carriage when the train, which had just left Mile End station, approached the tunnel.

He was travelling from his home in Rayleigh, Essex, towards Chancery Lane.

"Initially, people were panicking, you know, 7/7 was at the front of our minds, but then everyone calmed down pretty quickly.

"There was smoke and some of the windows broke," he said.

People screamed and a few fell over Ed Baines, commuter

Ed Baines, a 37-year-old university lecturer from Mile End, is a regular commuter on the Central Line and knew "something was up" after he felt a big bump.

"People screamed and a few fell over," he said. "You could feel the train was off the rail.

"There were some very worried faces and a few were sitting on the floor with their heads in their arms expecting something more to happen.

"Quite a few were quivering and shaking - it was very nerve racking all around."

People were scared the smoke was a "dirty" bomb Matthew Cameron

The Central Line train was travelling towards central London between Mile End and Bethnal Green when it is thought to have hit an obstruction on the track and derailed.

Matthew Cameron, a 32-year-old actuary from Woodford Green in Essex, was trapped on the train for about half an hour before being allowed to leave and walk down the tunnel back towards Mile End.

"The train performed an emergency stop, the lights went off and smoke blew into the carriage," he said.