A 15-year-old girl sustained multiple injuries after jumping from the fourth floor of Janakpuri's District Centre complex in west Delhi on Thursday, police said.
This was the sixth such incident at the complex in recent weeks.
The girl, identified as Prachi from Najafgarh in northwest Delhi, had come to the high-rise building with two of her friends, police said.
"Her friends rushed her to the Chandan Devi hospital, where her condition was declared critical," said a police official.
Police were investigating if it was a suicide attempt, an accident or a murderous attack.
On Wednesday, a 24-year-old man committed suicide by jumping from the fourth floor of the same complex. Police said that Karthik, as he was identified, was working on the third floor of Vishwadeep Towers in the same complex.
In another incident in June, a 19-year-old girl, Neha Kakkar, had committed suicide by jumping from the sixth storey of the Kirti Shikhar building in the complex.