The incident took place May 17 in east Delhi's New Usmanpur area, police said.
"Two of the three accused are minors. The third accused has been identified as Ajay who has been arrested. Ajay's younger brother has been sent to a juvenile home while the third accused is absconding," said a police officer.
The incident came to light after the girl, who was found in an unconscious condition in a street, gained consciousness two days after the incident and narrated the chain of events to her family.
A medical test confirmed rape and a case was registered, police said.
Her father lodged a complaint against Ajay and his brother, who lived near the girl's house, police said.