WLS-TV reports the shooting occurred at about 1:45 p.m. Friday outside Warren Elementary School in the Calumet Heights neighborhood on the city's South Side.
The 7-year-old girl was wounded in the thigh, and the 13-year-old girl was wounded in the hand, police say. Both were transported a local hospital. Mayor Rahm Emanuel arrived at the hospital to visit with the victims and their families shortly before 3:30 p.m.
Police say the victims were unintended targets, and that the shooter or shooters were inside a vehicle.