The girl was walking near the 4700 block of F Street at about 7 p.m. Monday when she was forced into a vehicle at gunpoint, was driven away and sexually assaulted, police said.
Police say the suspect dropped her off near 47th and Market streets in Chollas View about 15 to 20 minutes later. She then went for help at a nearby gas station and was taken to the hospital.
The reported attack prompted nearby Gompers Preparatory Academy Director Vincent Riveroll to urge parents to be cautious and look out for "suspicious behavior."
Riveroll wrote in the letter to parents that he also told students to walk in pairs or groups, and to go straight home after school.
The suspect was described as a black man who is about 40 to 50 years old with tattoos on his hands and halfway up his arm. He was wearing a black mask, shirt and pants.
Police say he was armed with a handgun and was driving an older black SUV or van.