An 83-year-old man and his son's live-in partner were stabbed to death allegedly by his grandsons in Uttar Pradesh's Kanpur Dehat district in the early hours of Thursday, police said.

The deceased were identified as Ram Prakash Dwivedi (83) and his son Vimal's live-in partner Khushbu (30). Vimal (63) was seriously injured in the incident that took place in Amrodha town, they said.

According to locals, there was friction in the family over Vimal's live-in relationship with Khushbu.

The accused, Akshat (18) and his stepbrother Lalit (42), went to Vimal's house and thrashed him, Ram Prakash and Khushbu. The two then stabbed Ram Prakash and Khushbu multiple times, said Superintendent of Police BBGTS Murthy.

While Vimal was trying to get out of his house, Munna, who earlier used to live with the Dwivedi family, saw him. Munna immediately informed Vimal's elder brother Kamal, who lives in the adjacent house.

Vimal was rushed to the district hospital and later shifted to Lala Lajpat Rai (LLR) Hospital in Kanpur, where his condition is stated to be critical, police said.

After receiving information about the incident, police acted promptly and nabbed Akshat and Lalit while they were trying to flee to evade arrest, Murthy said.

The two were apparently miffed with their father over his live-in relationship with Khushbu, said Additional Superintendent of Police Rajesh Kumar Pandey.

During intensive interrogation, they confessed to having killed Ram Prakash and Khushbu, he said.