The engine of the boat, which was travelling from Koraibeel to Gumifailed, stopped working midstream of the river and hit against the pillar of a bridge causing it to flip, Kamrup (rural) Deputy Commissioner Vinod Kumar Seshan told PTI.
As the boat capsized, the passengers, who were travelling to witness a boat race nearby, fell into the river which was in spate. While most of the passengers swam to safety, at least 30 were missing, Seshan said.
As night fell, the search operation was stopped to be resumed tomorrow morning, the police said.