City Superintendent of Police Lambodar Patel said the Mana police unit was dispatched after a distress call from the rented flat in Sahu Para, Dumartarai.
Sahu, 36, allegedly used a knife kept in the house to fatally wound his wife and sons before striking himself.
The 32‑year‑old Khileshwari Sahu and her 11‑ and 8‑year‑old sons were pronounced dead at the scene; the woman was transported to Dr. B. R. Ambedkar Memorial Hospital, where she was declared deceased.
Sahu was taken into custody, admitted for treatment, and is now under police interrogation; post‑mortems of the victims will be conducted at the forensic lab.
Investigators are probing the alleged motive of mistrust over his wife’s character and will release findings after the forensic analysis.