A witness, whose name was not reported, told police a car with two men inside tried to drive past the double-parked car, the Chicago Tribune said.
The witness said there was enough room for the car to drive past, but they stopped and exchanged words with a woman sitting inside the parked vehicle.
One of the two men allegedly got out of the vehicle and walked up to the eventual victim, who was standing on the sidewalk next to the parked car, the witness said. The victim told the men, "Go ahead on now, we're cool, we not on that."
The shooter lifted a handgun to the victim and said "Talk that [expletive] now," and fired a single shot, the witness said.
Police said the victim ran away and fell in an alley where he was picked up by an ambulance and taken to Advocate Christ Medical Center. The victim was "walking, talking breathing, living," police said.