The prisoners, reportedly divided on caste lines, clashed after tempers flared over circumstances of the death of an inmate Ram Balak Rai yesterday, the sources said.
Six prisoners, two of whom were identified as Anil Sharma and Chita Singh, were taken to the jail hospital after being injured in the clash, the sources said.
District Magistrate Jitendra Srivastava and Superintendent of Police Suresh Prasad Chaudhury visited the jail to review law and order, they said.
Taking a serious view of the matter, Chief Minister Nitish Kumar directed Inspector General, Prisons, Anand Kishore to visit the jail and investigate the incident.