An express train crashed with a passenger train at a station in eastern India early today, mangling the carriages and killing 56 people, railway police said.
Railway Minister Mamata Banerjee raised the possibility the crash could have been another case of sabotage, two months after Maoist rebels were blamed for a derailment that killed 145 people.
Ms Banerjee said she and top officials were rushing to the scene to investigate. "We have some doubts in our mind," she said.
The crash happened about 2am when the Uttarbanga Express slammed into the Vananchal Express as it left the platform at Sainthia station, about 125 miles north of Calcutta.
The smash 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 climbing through the debris searching for survivors were later joined by rescue workers using heavy equipment to cut through the metal.
Rescuers recovered 56 bodies from the crash site and 125 other people were injured, said Surajit Kaur Purkayastha, a top police official.
The two drivers of the Uttarbanga Express were among the dead, Ms Banerjee said.
The disaster was the second major train crash in the state of West Bengal in the past two months.
On May 28, a passenger train derailed and was hit by an oncoming cargo train in a crash that killed 145 people. Authorities blamed sabotage by Maoist rebels for that crash.
Accidents are common on India's sprawling rail network, one of the world's largest, with most blamed on poor maintenance.