Hundreds of passengers had a narrow escape on Sunday morning when an entire train jumped the rails at Liluah station, causing two of the coaches to slam against a platform while several more tilted sideways before coming to rest.

The Poorva Express had travelled barely 2km from Howrah station on its way to New Delhi when it went off course like a toy train on plastic tracks at 8.27am. Railway officials said nobody was injured.

Biplab Ghosh, travelling to Dhanbad, was about to take his first sip of tea on the train when he felt the coach rocking and swinging sideways. Then came the clang of metal against metal, followed by a violent jerk that felt like an earthquake. 'I realised that our coach had just rammed against a platform. Luggage kept in the overhead berths fell in a heap,' he recounted.

Biplab was in coach S1, which along with S2 swung sideways past the parallel tracks to crash into the platform 15ft away.

French national Laura Berteloot, travelling to Gaya with friend Simon Hellequin in the same coach, said she thought 'it was the end of me' when the accident occurred.

'The washroom collided against the luggage van and was smashed. Some of the berths got dislodged on impact. The entire coach was filled with dust,' said Laura, who boarded a special train to Delhi after being brought back to Howrah station.

An undetected crack in the tongue rail, a manoeuvrable point in the rails that allows a train to switch from one track to another, possibly caused the derailment, Eastern Railway engineers at Liluah station said.

'It seems that one of the wheels slipped off the track after crossing the tongue rail, triggering a domino effect,' an engineer said. 'It's also probable that a signalling problem was to blame.'

Sources said the tongue rail might have been damaged minutes before the Poorva Express arrived. 'A team of gangmen was working on the track minutes before the train came. We are inspecting if a portion of the track got damaged during the maintenance job,' an Eastern Railway official said.

What saved the passengers was the speed of the train. 'The Poorva Express was moving at 10 to 15kmph when the accident occurred. The average speed of the train is 63kmph, though it can travel at 130kmph. Derailment at higher speeds would have been catastrophic,' an official said.

The train driver slammed the brakes when the motorman of a goods train waiting on the parallel track some distance behind the platform alerted him to the derailment.

'I saw the coaches at the rear trembling violently. Moments later, they started to jump the rails one by one. I immediately alerted the motorman of the Poorva Express by waving a red cloth,' said Jishnu Nandi, the motorman of the goods train.

All 12 coaches of the train, barring the luggage van and the engine in front, were derailed. Some of the coaches that tilted sideways would have toppled over had they not been all connected. The metal wheels of a few coaches sliced into the concrete strip between the rails. Inside the coaches, luggage was strewn across the floor.

Apart from S1 and S2, coaches S10 and S11 were severely damaged.

Train movement along platform numbers four and five of Liluah station hadn't resumed until late on Sunday. Three trains were cancelled and several were diverted.

Eastern Railway has set up a committee to investigate the derailment.

'An inquiry committee comprising five officers of senior administrative grade, headed by the chief safety officer of Eastern Railway, will investigate the derailment,' Eastern Railway said in a statement.

The Poorva Express was the most popular train from Calcutta to Delhi before the Rajdhani Express was introduced. It used to be known as the Deluxe Express because of its comfort and punctuality. It covers the distance between Howrah and New Delhi in 24 hours.