The victims, who were to visit a nearby Hindu temple, had gotten off another train and were trying to reach the other side by walking over the rail tracks when they were struck by the oncoming Rajyarani express train, a police official told the Hindustan Times.
The incident occurred in the remote Saharsa district in the eastern state.
The report said at least 30 more people were injured. They were taken to a local hospital, where an unknown number were reported to be in critical condition.
Various reports said the incident triggered angry protests by residents of the district, who set fire to some of the Express train's coaches as well as two other stationary trains. They also attacked the railroad station, forcing railway officials and workers to flee the scene.
NDTV said most of the victims were women and children. The report said the express train was traveling about 50 mph when it plowed into the group.
A senior railway official said the express train was not scheduled to stop at the station and had been given a green signal to pass, the Times reported. The official said the driver of the train applied emergency brakes but it was too late to stop the train.