A senior Delhi Police official said that the incident yesterday took place when the alleged victim was alone at her house in Madangiri and her mother was away for work.
The accused allegedly used different pretexts to get the two minor brothers of the girl to go out of the house and then assaulted her while she was sleeping, he said.
"She tried to resist but the accused threatened her and also told her he would thrash her if she spoke of the incident to anybody," the official added.
He further stated that by the time the girl's brothers returned home, the accused had left.
"The victim recounted the entire incident to her mother after she returned from work. The mother then made a PCR call following which a police team reached the scene and took the girl to AIIMS for a medical examination," he said.
"We arrested the man immediately and the assault was also confirmed," the official added. The victim's parents are professional beauticians and work at different salons.