The incident took place on August 14 when Sushil who was known to the girl, introduced her to one Shyam Kacholia at the latter's flat in Jadon Nagar locality, police said.
The accused offered her a drink laced with sedatives following which she lost consciousness, police said, adding, the duo raped her.
Later, their friend Fateh Singh also raped the girl, they said.
The incident came to light yesterday when the girl lodged an FIR with Bajaj Nagar Police Station.
The matter is being probed to ascertain more facts, police added.