Superintendent of Police Praveen Tripathi said local people were digging earth on the 'char'(a temporary island) at Santra Bazar locality of Gopalnagar gram panchayat when the skulls and bones were found.
There would be an investigation and the bones would be sent to the forensic laboratory to identify the victims, he said.
There had been no crematorium or cemetery in the area nor was there any reports of mass murder or incidents of capsizing of a boat in the past, Tripathi said.