The students had gone for a bath in the river when they were drowned, police said.
One body was identified as that of 8-year-old Tarun.
Divers were pressed into service to retrieve the bodies of Suraj (10) and Bittu (12), who were siblings.
They were all residents of Saldih bustee in the industrial township of Adityapur.
All the three were students of Ram Krishna Mission school in Jamshedpur, the sources added.