The incident occurred at 1:30 am when the train was running between Khemasoli and Sardiya stations, about 135 km from Kolkata.
But confusion prevailed over whether a bomb blast by Naxals or an act of sabotage by removal of fish plates led to the derailment. Police said about a one-foot section of track was missing.(One foot section of track missing: Police chief)
While Home Minister P Chidambaram said that train derailment in West Bengal appears to be a case of sabotage, Railway Minister Mamata Banerjee says a blast as part of a "calculated attack" caused the Gyaneshwari Express to first derail and then get hit by a goods train. (Read:Bomb blast caused derailment: Mamata)
Finance Minister Pranab Mukherjee, however, contradicted the statements of both the ministers and said, "I don't know what is the cause. When I last checked, there was no evidence of either an explosion or sabotage activity." (Read: Top UPA Ministers divided?)
Meanwhile, the West Bengal police have said that Maoist-backed organization People's Committee against Police Atrocities (PCPA) has claimed responsibility for the accident.
"Two posters belonging to the Maoist-backed People's Committee against Police Atrocities (PCPA) have been found at the site," West Bengal Director General of Police Bhupinder Singh told NDTV.
Bodies of the passengers were removed from the mangled remains of the ill-fated coaches and the injured taken out with the help of gas cutters, a South Eastern Railway spokesman said.
"Sixty five bodies have been recovered. The toll could go up," West Bengal Home Secretary Samar Ghosh said.
He also said that the over 200 injured have been shifted to different hospitals and the condition of some of them is critical.(Watch: Injured rushed to Kharagpur hospital)
"Some of the critically injured people have been brought to Kolkata for surgical treatment," he said, adding that 30 of the bodies have been sent to various hospitals for post-mortem.
Five of the 13 derailed coaches fell on an adjacent track and were hit by a goods train coming from the opposite direction, Additional Superintendent of Police, Jhargram, Mukesh Kumar said.
Indian Air Force helicopters were pressed into service at the accident spot to airlift some of the injured to the hospitals.
Railway Minister Banerjee, who reached the accident spot in the morning, had also said a patrol engine had passed through the area half an hour earlier, but the timing of the blast proved disastrous with a portion of the line being blown away.
She also announced a compensation of Rs 5 lakh for the next of kin of each of the dead and Rs 1 lakh for the injured.
President Pratibha Patil, who is in China, and Prime Minister Manmohan Singh expressed grief over the loss of lives in the incident. The Prime Minister announced Rs two lakh to the next of the kin of the deceased and Rs 50,000 for the injured. He has also asked the rail ministry to ensure all help to passengers. (Read:PM to Rail Ministry: Ensure all help)
South Eastern Railway spokesman Soumitra Majumdar said the train had 24 coaches. After the explosion, 13 including 10 sleeper coaches, derailed of which five were hit by the goods train coming on the opposite track.
An unreserved coach, the pantry car and luggage van also derailed, he said.
Relief officials used gas cutters to extricate trapped passengers and bodies from the mangled remains of the affected coaches. Passengers' belongings lay strewn scattered on the tracks.
Angry passengers said the first signs of relief came only around 5 am, three-and-a-half hours after the incident.
Nine of the coaches which were not damaged in the blast took the injured and the other passengers to Kharagpur where they were admitted to a hospital. (Read: List of injured)
Anti-Maoist forces were at the spot and assisting the police and rescue personnel in extricating the bodies from four badly-damaged sleeper coaches S-5, S-6, S-7 and S-8. (Read: Chronology of Maoists' targeting trains in West Bengal, Jharkhand and Bihar)
West Bengal Chief Minister Buddhadeb Bhattacharjee asked state Finance Minister Asim Dasgupta to immediately rush to Sardiha, the site of the accident.
"I have been asked by the chief minister to rush to the accident site with six special rescue teams and three mobile ambulances," Dasgupta told PTI before leaving for the accident spot.
The state government would bear the treatment cost of the injured passengers, Chief Minister's Secretariat sources said.
"State government has already rushed preliminary rescue teams with doctors and ambulances and more will follow," sources said.
Senior railway officials including Railway Board Chairman S S Khurana and DG RPF also rushed to the spot.
A relief train left Kharagpur with a team of 12 doctors and 20 paramedics as also two doctors from the Kalaikunda airbase, the officials said.
"The S-5 and S-6 coaches bore the maximum brunt of the impact," Palash Ganti, a passenger, said.
Ganti, who was travelling in the B1 coach, said when he looked out of the window he found that half of the coaches had derailed and a goods train on the opposite tracks hitting them.
"At first, we thought Maoists have attacked to loot the train. When the accident happened no RPF personnel were present on the train," said another passenger.
Helplines have been set up at Kharagpur - (03222) 255751 and 255735, Howrah -- (033) 26382217, besides a toll free number 10722. Helplines have also been set up at Tatanagar (0657) 2290324, 2290074, 2290382, at Rourkela (0661) 2511155, Chakradharpur (06587) 238072 and Jharsuguda (06445) 270977. (With PTI Inputs)