Maoist rebels have claimed responsibility for sabotaging a high-speed train in eastern India, killing up to 80 people after it smashed into the path of a goods train.
Local television showed the mangled wreckage of carriages of the Mumbai-bound express from Kolkata.
The death toll could rise as many passengers are still trapped. Well over 100 people have been injured.
Railways Minister Mamata Banerjee said the train was derailed by a 'severe bomb blast'.
However, local officials said they are also looking at evidence that metal plates used to secure adjoining sections of track had been removed.
The Maoist-backed People's Committee against Police Atrocities claimed responsibility for the attack in a call to the Press Trust of India.
The crash occurred in an area known to be a stronghold of Maoist rebels.
Maoists, who say they are fighting for the rights of the poor and landless, have attacked trains in the past and have stepped up attacks in recent months.
'The driver heard a loud noise which indicates there could be a blast. A detail investigation will reveal more, but definitely there was lot of tinkering done to the tracks,' Vivek Sahay, a senior railway official, told reporters.
Prime Minister Manmohan Singh has described the Maoist insurgency as India's biggest internal security challenge and his Congress-led government has been under increasing political pressure to deal with the insurgents.
