Carpentersville police responded to a call of shots fired at about 12:03 a.m. at a restaurant in the 1300-block of Kings Road, ISP said.
ISP said a Carpentersville police officer saw a suspect "actively shooting at a person."
The officer then shot and killed the suspect, who has yet to be identified.
ISP said the suspect allegedly shot two victims. Both were taken to the hospital, one was in critical condition.
No officers were injured.
ISP called the shooting an isolated incident that stemmed from a domestic violence case.
No other information was available.