At least a dozen people were missing when their boat capsized after colliding with another boat on the Ganga river near the Bihar capital Sunday, an official said here.
The over-crowded boat sank in the swollen river after colliding with a boat laden with sand at Danapur in Patna district.
The district administration, along with a National Disaster Response Force (NDRF) team, has launched rescue operations, officials said.
"All the people on the boat are feared drowned," an official said.
The threat of floods is looming large in several districts of north Bihar following incessant rains for the past several days in neighbouring Nepal.