"The accident occurred when a passenger bus veered off the road and overturned on a highway at Beldanga in the state's Murshidabad district this morning," a senior police official said.
Seven passengers died on the spot, and the injured were admitted to a government hospital where the condition of nine people were said to be serious, he said.
Eye-witnesses told cops that the bus was travelling at high speed and the driver suddenly lost control of the vehicle, leading to the accident.
"A probe has been ordered into the incident," the official added.
The accident came three days after six people were killed and 25 others injured when a bus in which they were travelling fell into a roadside ditch in the state's West Midnapore district.
Xinhua/AIMD