The incident came to light this afternoon when the daughter of the deceased informed the neighbours after phone calls to her family went unanswered, police said.
The door of the house was broken and the bodies of Purshottam Das Singh (70), a retired bank employee, and his wife Sharda (65) were recovered. They were killed with a sharp-edged weapon, police said.
The couple's son Gaurav (30) was found in a seriously injured state and was admitted to hospital.
A criminal gang is suspected to be behind the crime, they added.