Sub Divisional Magistrate of Dhanghata Pramod Kumar said there were 18 people on the ill-fated boat of which 14 have been rescued.
The villagers mistook the Delhi Police personnel as child lifters and surrounded their vehicles, the police said.
18 others were injured when a village head and his supporters allegedly opened fire on a rival group, leading to the clash.
While villagers gathered and indulged in vandalism including breaking a wall of a nearby madrasa, cops have registered a case against two for cow slaughter.
As the captains of the teams - Anwarul Haq and Phoolchandra - belonged to different communities, the clash took on a communal colour.