Officers responded at about 10:40 p.m. to the 600-block of Wheeler Avenue.
Officers found a 15-year-old boy wounded in the head and he was transported to St. Jospeh Medical Center in critical condition, police said. The boy was then transferred to Lurie Children's Hospital.
A 14-year-old boy was also injured and transported to St. Joseph Medical Center, police said.
Investigators said the shooting occurred at West Park and detectives canvassed the scene for evidence.
Further details were not immediately available.