A 35-year-old woman hanged her three children and then herself inside a cow shed in Bihar's East Champaran on Friday, police said.
The reason behind the suicide is not yet known, police added.
The dead were identified as Dhanpati Devi, her daughter Sandhya Kumari (6) and two sons - Ritesh (3) and Chhotu (four months).
The woman's husband works outside of the village.
Villagers found the bodies hanging from the ceiling of her cow shed at Chhota Baishahan village.
The police are investigating the matter. The bodies have been sent for post-mortem examination.