According to MANA, The incident took place in the evening, when people were using the vessel to go to watch kite-flying celebrations to mark a harvest festival.
The boat was carrying 50 people, more than its capacity of 30, and it capsized not far from the shore in the state capital Patna, state Disaster Management Minister Chandrashekhar told Reuters.
"We believe a minimum of four to five (more) bodies may be in the river," said Chandrashekhar, who goes by one name only.
He added that rescue operations were under way.