It happened around 4:30 p.m. Saturday in the 800 block of East Washington Lane.
Police say a 32-year-old woman was making deliveries for a private company at the location when a gunman forced himself into her vehicle.
The man forced the woman to drive to another location and raped her, police say.
The suspect is described as a black male in his 20s, who was last seen wearing a black hooded sweatshirt and blue jeans.