The victims have been identified as Chandu Lal (70), his wife Gullu Devi (65) and their son Rakesh (30). Their throats were slit with a sharp object and Rakesh's limbs were tied with a rope, said DCP (North) Madhur Verma, adding that the motive behind the crime could not be ascertained yet.
The family lived in two single-room accommodations - one on the third floor and the other above that - in the same building at Sarai Basti locality near Shastri Nagar in Sarai Rohilla.
The third floor was found to be in a disorganised state but objects in the fourth floor appeared to be untouched, said the official.
The incident was reported by a neighbour at around 7.30 PM today and a police team was rushed to the spot. Neighbours also told the police that the family was last seen on Wednesday.