The details on the casualty is not known yet, and there are no reports yet on any passenger being rescued.
The engine of the boat, carrying the passengers from Chaygaon to Champupara to attend a boat race, failed to function in the middle of the river and hit against the post of a bridge, Kamrup (Rural) Deputy Commissioner Vinod Kumar Seshan said.
The local residents have begun rescue operations and NDRF and SDRF personnel have rushed to the spot.
Seshan, however, said many may have swam to safety to the other bank of the rive, but reports were yet to come in.
Senior police and civil officials have rushed to the spot and the hospital authorities nearby have been alerted.