Chicago Police said the shooting took place in the 700 block of East 50th Street near South Cottage Grove Avenue.
Two 17-year-old boys were each shot in the ankle and were transported to the University of Chicago Medical Center in stable condition.
The third victim, a 21-year-old man, was shot in the head and taken to the University of Chicago Medical Center in critical condition.
Police did not release information about the circumstances of the shooting. No one is in custody.
The shooting is under investigation.