A freight train smashed into the rear of a stationary passenger train in India's West Bengal state on Monday, killing at least 15 people and injuring dozens, police said, in an accident that railway authorities blamed on driver error.

Media showed images of the pile-up, with containers from the goods train strewn nearby, and one carriage left nearly vertical after the accident, which comes just over a year after a signalling error caused one of India's worst rail crashes.

Fifteen bodies were pulled from the mangled carriages, Abhishek Roy, a senior police official in the eastern state's district of Darjeeling, the site of the accident, told Reuters.

Fifty-four people were injured and rescue teams from the police and national disaster response force were working to clear debris from the derailed carriages, Roy added.

The goods train hit the Kanchanjunga Express travelling to Kolkata, the capital of West Bengal, from the northeastern state of Tripura, driving three carriages of the passenger train off the rails.

It was not immediately clear how many passengers were on board at the time.

Rescuers used iron rods and ropes to work free one carriage of the passenger train that had been swept upwards to lodge on the roof of the freight train by the impact of the collision.

The dead included the driver of the freight train and a guard on the passenger train, Jaya Varma Sinha, the head of the railway board that runs the countrywide network, told reporters.

The accident happened after the driver of the freight train disregarded a signal, Sinha added.

Rescue work has been completed, Sinha said, and authorities are working to restore traffic, with the damage less extensive than initially feared.

"The guard's compartment in the passenger train was badly damaged," she added. "There were two parcel vans attached ahead of it which reduced the extent of damage to passengers."

Nearby residents heard a loud crash and saw the pile-up upon going to investigate, several told the ANI news agency, in which Reuters has a minority stake.

Prime Minister Narendra Modi offered condolences on the loss of life and said Railway Minister Ashwini Vaishnaw was on his way to the site.

About 288 people died a year ago in the neighbouring state of Odisha, in India's worst rail crash in more than two decades, caused by a signal failure.

Opposition parties criticised Modi's government for its record on rail safety.

"The increase in railway accidents in the last 10 years is a direct result of the mismanagement and negligence of the Modi government, which results in loss of lives and property of passengers on a daily basis," Modi's main opponent and Congress party leader Rahul Gandhi said in a post on X.