The couple, identified as Bhimchandra Pratap Singh (60) - a retired Assistant Controller in the electricity department and his wife Hembala Devi (45) were battered to death by the assailants with rod and other blunt objects at their residence in Barauni thermal power plant residential colony, Deputy Superintendent of Police Lalit Mohan Sharma said.
The motive behind the double murder was under investigation, he said.
A forestic team from Patna has rushed to the spot to collect evidence, he said.
Singh had retired from service in June this year and was staying at the Barauni thermal power residential colony since then, Sharma said.
In a related incident, a secondary school teacher, identified as Dilip Kumar Chaudhary (40) was shot dead by unidentified assailants near Lohia Nagar railway crossing last night, Superintendent of Police Chhatraneel Singh said.
A dispute over construction of the school building with another teacher could be the reason behind the murder, he said.
The accused teacher was arrested and a case lodged against him in this connection.