Police say the man approached an 18-year-old woman in the 3700-block of West Harrison, pulled out a gun and forced her into an alley about a block away.
The attack happened around 4:45 p.m. about five blocks from the nearest police station.
Police say the attacker is in his late teens, about 6 feet tall, 160 to 180 pounds. He had a fade haircut, chipped front tooth, a tattoo of the letter "M" on his neck and tattoos on both arms. He wore a white t-shirt, blue jeans and black and white gym shoes.