The girl told police she was walking home when the man drove up and exposed himself.
Police released a cellphone image of the car driven by the alleged offender, described only as a Hispanic man. The car is a lime green Ford hatchback.
Those with useful information to share are encouraged to call Area Central Detectives at (312) 747-8380.
In the wake of the crime, police offered this advice:
• Always be aware of your surroundings,
• Walk/Ride in pairs or groups.
• Dial 9-1-1 to report suspicious activity immediately.
• Never pursue a fleeing assailant; instead, provide the information to the police.