The mishap happened at Sherpur Ganga ghat when the youths were taking bath, Station House Officer of Maner police station, Rajiv Ranjan said.
The youths went towards deep water of the river in course of taking bath and drowned, the SHO said.
Body of only one has been found so far and search is on for others, he added.
State Disaster Response Force (SDRF) personnel are carrying search for the five other victims, Ranjan said.