The bus was going from Jhargram, Midnapore district to Durgapur, Burdwan district. According to sources, at least 12 persons have been rescued.
Many people are still missing and the rescuers feared that they may have been swept away.
The flash flood swept the bus 300 metre downstream when the bus was crossing a culvert over Bhairab Baki River in Bankura.
The tragic incident took place around 1:30 pm. The superintendent of Bankura police, Mukesh Kumar has been quoted as saying, "We are not in a position to comment on the number of passengers in the bus. About 15 passengers have so far been rescued. Our first priority is to save the passengers."
Flash flood often happens in the region as the Bhairab Baki is a rain-fed river. Most parts of the state have been experiencing heavy rains since last two-three days.