The shooting occurred around 7 p.m. near 4th Street and Washington.
Police said the victim was inside a car that came to a stop in a vacant lot. No one else was injured in the shooting.
It's unclear if the man was shot by a pedestrian or from another vehicle. The Madison Police Chief requested the Major Case Squad's help in the investigation since the Madison police force is not large. The Major Case Squad also brings in evidence technicians from the Illinois State Police.
Police did not have a motive or any suspects.