New Delhi, India (CNN) -- Investigators were searching for bodies in a mangled wreck Saturday, a day after two trains crashed and killed at least 98 people in eastern India, officials said.
Maoist rebels are suspected of causing the crash by removing the fasteners securing the tracks, police said.
Authorities identified some suspects, but had not yet made any arrests, said Bhupinder Singh, police chief in West Bengal state. He said "quite a few" people were involved.
At least 115 passengers were injured when 13 cars of the Mumbai-bound Lokmanya Tilak Gyaneshwari Express derailed, capsized on a parallel track and were slammed by a cargo train, authorities said.
More than a dozen bodies may still be trapped inside the wreckage, said N.S. Nigam, West Midnapore district magistrate.
Singh told reporters Friday that officers had found Maoist posters claiming responsibility for the attack.
"It appears to be a case of sabotage where a portion of the railway track was removed. Whether explosives were used is not yet clear," Indian Home Minister P. Chidambaram said in a statement Friday.
Manoj Verma, the district police superintendent, said Friday that investigators were looking into the possibility that "fishplates," which secure rail joints, were missing from the track.
The role of Maoists "cannot be ruled out," Verma said.
India regards Maoists as its gravest internal security threat.
More than 70 officers were killed in a suspected Maoist ambush in Chhattisgarh state last month in what was seen as one of the most daring attacks by the left-wing guerrillas on Indian security forces.
The insurgents, on the other hand, have claimed since the 1960s to be fighting for the dispossessed.
In February, Chidambaram said that more than 900 people, including almost 600 civilians, were killed in Maoist-related incidents in 2009.
About 200 suspected rebels were also slain as forces moved into areas under insurgent control, he said.