At least 40 passengers were injured when a passenger bus travelling from Berachampa to Karunamoyee in the Kolkata suburb of Bidhannagar fell into a canal in Rajarhat on Friday morning.
Panic-stricken passengers screamed for help and local residents rushed to the scene and carried out rescue operations, initial reports said.
The injured were taken to Deganga Hospital and a nearby private hospital.
According to police, the bus broke through a railing and plunged into the Rajarhat–Haroa canal around 7:30am.
The vehicle was carrying about 50 passengers at the time.
Police reached the spot and began questioning the driver and helper to determine if the accident occurred due to drowsiness or any other cause.
An injured passenger said, "I was going to the office in Salt Lake. The bus was full. The driver lost control while trying to overtake another bus, and ours fell into the canal."
Eyewitnesses said the bus was speeding before it lost control and overturned into the canal. Police have begun an investigation to determine the cause of the accident.