A 25-year-old man allegedly stabbed to death his father, mother, sister and grandmother following a quarrel in southwest Delhi's Palam area, police said on Wednesday.
The accused, identified as Keshav, has been arrested, they said.
The deceased have been identified as father Dinesh, mother Darshana, sister Urvarshi and grandmother Deewana Devi, they said.
On Tuesday at around 10:30 pm, police received information about a quarrel on the upper floor of a house, a senior police officer said.
After reaching the spot, police found four members of a family dead in their house, Deputy Commissioner of Police (southwest) Manoj C said.
Relatives caught him and handed over to police
The caller and his relatives caught hold of the accused and handed him over to the police, he said.
The primary investigation revealed that Keshav did not have a stable job. He used to work in a company in Gurgaon and left the job a month ago, police said.
Prima facie it seems that the accused killed his family following an argument, they said.
A case under section 302 (murder) of the Indian Penal Code has been registered in Palam police station and further investigation is on, police said.
"I returned home around 9.15-9.30 pm. 10 minutes later, I heard my cousin Urvashi scream for help. I went upstairs and knocked on the door. We tried to break it open. My cousin Keshav called us out from inside and told us to go away, saying it is a family matter," said Kuldeep's relative.
Further investigation into the matter is underway.