An express train collided with a passenger train at a station in eastern India early Monday, mangling the carriages and killing at least 49 people, railway police said.

The crash happened at about 2 a.m. local time, when the Uttarbanga Express slammed into the stationary Bananchal Express as it was about to leave the platform at Sainthia station about 200 kilometres north of Calcutta.

The collision destroyed two passenger cars and a luggage car, turning them into a tangle of twisted metal. The passenger cars were reserved for those on the cheapest tickets and such carriages are usually packed to capacity.

The force of the crash was so intense the roof of one car flew into the air and landed on an overpass above the tracks. Local residents climbed through the debris searching for survivors. They were later joined by rescue workers using heavy equipment to cut through the metal.

Rescuers recovered 49 bodies from the crash site, and about 100 other people were injured, said railway spokesman Samir Goswami. The cause of the crash is under investigation, he said.

Accidents are common on India's sprawling rail network, one of the world's largest, with most blamed on poor maintenance.