Subhash Kumar, a 43-year-old who lost his job at a scooter repair shop, took poison with his wife after poisoning thier children - aged between seven and 14 years - late Friday at their house in Piyarwa Pokhra village in Mirzapur district, some 300 km from Lucknow.
"Preliminary investigations indicate that poverty drove the family to consume poison. It was Subhash who made his wife and four children consume the poison," police inspector Deepak Dubey said in Mirzapur town.
Subhash's wife Seema, 39, and his two daughters - Punni Devi, 9, Rani, 14, - and son Rajesh, 12, died instantly. Subhash and his seven-year-old daughter Mona are battling for life.
The incident came to light when some villagers went to meet Kumar at his house and found the six heaped on the floor.
Kumar was reportedly finding it difficult to take care of his family for weeks after losing his job.