The incident was reported from Rohini this morning.
The victims, originally hailing from Etah in UP, were identified as 55-year-old Y P S Chauhan, owner of a godown for chemicals in Shahbad Daulatpur, his wife Rekha (50) and daughter Karishma (22).
While Chauhan was fatally hit on his head, his wife and daughter were strangled.
"The house was not ransacked but a mobile phone is missing. Robbery is not the motive. Entry into the house was friendly which suggests that someone known to the family could be behind it," a senior police official said.
The murders came to light when a local priest's daughter went to their house. Rekha was to join the priest and nine other women on a pilgrimage to Vaishno Devi this morning.
The priest send his daughter to the house when Rekha did not reach at the time of departure.
"She found the gate open, she went inside and found Chauhan lying in a pool of blood. She raised an alarm and neighbours informed police," the official said.
Investigators claimed the murderer cleaned the room in a bid to clear evidences.
