Unidentified killers murdered mother and daughter and the husband sustained grievous injuries in the Chak Miyan Poore Khurd village in Prayagraj.
The murderers however spared the granddaughter, aged 7, who was asleep beside the woman.
The husband, identified as Bajrang Bahadur Bajrangi, 50, has been admitted to a hospital in critical condition.
The deceased have been identified as Prema Devi, 45, and her daughter Tanu Patel, 18, who were attacked with sharp weapons while they were sleeping.
The villagers spotted the bodies in a pool of blood on Wednesday and informed the police. Bajranj was found lying unconscious in another room.
Forensic experts and a sniffer dog squad was rushed to the spot but the motive behind the killings is yet to be ascertained.
Money and jewellery were also stolen.
Police said that the son of the critically injured house owner had committed suicide a couple of years back. The son’s wife had left the home, leaving behind her minor daughter.
Industrial Area chowki in-charge Manoj Kumar said several teams of police have been set up to investigate the case and arrest the accused.