Nine people have died and 45 others were injured when a train derailed in India's West Bengal state, officials said.

Rescuers in the Jalpaiguri district found four more bodies overnight as they cleared the 12 mangled coaches of the train.

The coaches went off the rails during the accident on Thursday, with three overturning.

Rajiv Jain, a rail ministry spokesman, said rescue work is completed and the track is being cleared to restore train services.

Railway authorities have ordered an investigation into the cause of the derailment.

Images from the scene after the accident showed passengers stuck in twisted metal and debris as rescuers tried to pull them out.

The train was on its way to Gauhati in Assam state from Bikaner, a city in Rajasthan state, when the accident occurred in Jalpaiguri.

All of the injured are being treated in hospital, senior police officer Debarshi Dutta said.

Senior railway official Guneet Kaur said the cause of the accident was being investigated. She said the government would provide financial compensation to families of the deceased and all of the injured.

Accidents are common on India's massive but aging railway network. Safety standards are an ongoing concern over the state-run system, which operates 9,000 passenger trains and carries about 23 million passengers every day.

In 2016, 127 people were killed when 14 coaches derailed in Uttar Pradesh state in one of India's worst train accidents.