Police say the girl was walking in the area of 2nd and Tree Street when a young man pulled her behind a plastic covering of a scaffold and raped her.
Officials say the girl had been participating in Mummers festivities on 2nd Street and may have been intoxicated.
Residents on Tree Street next to the scaffolding say they heard screams and saw the suspect walking away when they came out to investigate.
Police were able to apprehend the suspect a few blocks away because of the heavy police presence in the area.
The name of that suspect has not been released.
The 16-year-old was taken to Children's Hospital of Philadelphia for evaluation.
The incident remains under investigation.