Bodies of Seema (26) and Parul (24) were found hanging from the ceiling fan around 3.30 PM yesterday. No suicide note was recovered, a senior police official said.
Seema was a teacher at a play school, the official added.
No foul play is suspected so far. An inquest has been initiated into the matter but the cause behind the extreme step is yet to be ascertained, police said.
Seema and Parul's mother had passed away in 2009 and their father died two years later, following which the sisters started living with their elder brother, who lives in Rohini Sector 23 with his second wife.
From preliminary investigation, it emerged that the sisters were depressed and they did not have a good relationship with their sister-in-law. But nothing can be concluded at this stage, the official added.