The incident took place near Hari Nagar locality, police said.
Five members of a family, identified as Nakul Prasad (35), his wife Puja Devi (30) and their three children Kajal Kumari (11), Kamini Kumari (9), and Anmol Kumar (6) consumed poisonous substance apparently due to financial distress, Deputy Superintendent of Police (DSP), Fatuha, Anuj Kumar said.
All of them were found lying in an unconscious state by the local people who informed the police about the incident, the DSP said.
A probe was on to find out circumstances in which the family members took the extreme step, the DSP said.
The victims were living in a rented accommodation at Danapur in the outskirts of Patna, he said.