A passenger train has derailed in eastern India, killing four people and injuring dozens, a government official said.

All 21 coaches of the North-East Express train, on its way to the state of Assam from New Delhi, derailed near the Raghunathpur rail station in the Buxar district of the state of Bihar, magistrate Anshul Agarwal said.

Two of them overturned and rested on their sides.

Local residents rushed to the scene and helped passengers exit the derailed coaches. Ambulances later arrived and hospitals were alerted to receive injured passengers, said police officer Deepak Kumar.

DK Pathak, a railroad official who was on the train when it derailed, said most injuries occurred in one of the derailed coaches.

The cause of the derailment is being investigated.

Early reports said 70 passengers were injured, with 31 taken to hospital.

“The train was coming at a normal speed but suddenly we heard a loud sound and saw a plume of smoke rising from the train. We rushed to see what happened. We saw that the train had derailed,” the Press Trust of India cited Hari Pathak, a person living in the area, as saying.

In June, India had one of the country’s deadliest rail crashes involving two passenger trains that killed more than 280 people and injured 900 others. A malfunction with the signal system was found to have caused the accident.