Police said the shooting happened at Hamlin Park in the Lakeview neighborhood's 3000-block of North Hoyne Avenue just before 2:30 p.m.
A 15-year-old boy was in the park when two armed males approached him and took out guns, police said. At least one of the suspects fired at least one shot at the victim, striking him in the back.
The victim was transported to Lurie Children's Hospital in serious condition.
The suspects fled the scene.
There is no one in custody, and area detectives are investigating.
Police did not immediately provide further information about the shooting.
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