A railroad ministry spokesperson said 10 to 12 coaches of one train derailed before being hit by another passenger train coming from the opposite direction.
The death toll from the derailment of two passenger trains in India has risen to 120, according to a media report.
The Press Trust of India quoted state Fire Services Chief Sudhanshu Sarangi as saying that many bodies had been found and that the number is likely to increase. He also said more than 800 people were hurt.
The accident happened in eastern India, about 220 kilometres (137 miles) southwest of Kolkata, officials said.
Amitabh Sharma, a railroad ministry spokesperson, said 10 to 12 coaches of one train derailed, and debris from some of the mangled coaches fell onto a nearby track. It was hit by another passenger train coming from the opposite direction.
Up to three coaches of the second train also derailed.
On Twitter, Prime Minister Narendra Modi expressed his solidarity with the victims and assured that rescue operations were underway.
According to the region's top bureaucrat, Pradeep Jena, nearly 500 police officers and rescuers were dispatched to the scene, with 75 ambulances and buses.
Rescuers were attempting to free 200 people feared trapped in the wreckage, said D.B. Shinde, administrator of the state's Balasore district.
An investigation has been launched to determine to cause of the accident.
Despite government efforts to improve rail safety, several hundred accidents occur every year on India’s railways, the largest train network under one management in the world.