Rivals of Kamlesh Rai of the village stormed Rai's house and stabbed Rai and five other family members, sources said.
Kamlesh Rai (55), Satyendra Rai (50), Shanti Devi (45) and Vikas Kumar (22) died and their bodies were brought to a government hospital for postmortem, sources said.
Other two who were injured in the incident were admitted to a hospital for treatment.