Five others are still missing and search operations have been continuing to trace the rest of the missing persons.
Official sources said they have been trying to find whether they swam to safety to the other side of the river or failed to come out of water.
The boat capsized near Khajuri Ghat in Nuwaon block in Rohtas district. The boat carrying over 60 pilgrims of Uttar Pradesh was coming from Akhani village after attending an Urs fair.
While a majority of the people managed to swim to safety, six had gone missing in the mishap.