The incident happened around 12:30 a.m. Monday in the 1000 block of Wagner Street.
According to police, the victim said she was walking home when an unknown man approached her from behind and told her to get in his car.
The girl says she broke free and continued walking home when the man grabbed her again, threatened her with a handgun and sexually assaulted her.
The male is said to have let her go when an unknown passerby looked in the direction of the incident.
The suspect is described as a black male about 20-30 years old, about 5 foot 7 inches tall, weighing about 160 pounds, with sideburns. He is said to have been wearing a white tank top and tan pants.
The weapon is described as a black handgun.