Officers responded to a call of shots fired at a home in the 1300 block of Chestnut Street in the northern suburb around 12 a.m., Waukegan Chief of Police Keith Zupec said in a statement.
When officers arrived, they located a vehicle parked in the driveway of the home that had been shot multiple times, police said.
Officers also discovered a victim inside the vehicle. The victim appeared to be the driver, according to police.
The victim, a Waukegan man in his 40s, had been shot numerous times and was pronounced dead at the scene, police said. The man's identity was withheld pending notification of family and the completion of an autopsy by the Lake County Coroner's Office.
Zupec said the motivation for the shooting was unclear, but investigators do not believe the attack was "random". Police did not reveal the number of bullet casings that were recovered or their calibers.
Anyone with information is asked to contact the Waukegan Police Department tip line at 847-360-9001.
The Waukegan Police Department's Criminal Investigations Division continues to investigate.