The incident happened when the two, identified as brothers - Ninesh Kumar (6) and Vivek Kumar (8) - residents of Puraniya village under Lalganj police station, went for a bath in a pond at neighbouring Pahetiya village, they said.
Both ventured into deeper part of the pond and drowned, Station House Officer of Sadar Police station Mohammad Abbas said, adding that locals tried saving them but failed.
The bodies were ultimately fished out by divers and sent for post mortem.