The officer was trying to break up a fight in the parking lot outside the Stadium nightclub at 16300 Dixie Highway when a man approached him with a gun at about 3:30 a.m., police said. The officer opened fire and killed the man.
The victim was identified as Donte Jones, 36, of Maywood.
"I don't know really too much but you know, everybody got to running, everybody got to shooting, I heard about 8 shots, I see two people, two people got shot, one person dead," said witness Johnthan Smith.
The Stadium nightclub used to be known as "Adrianna's" which closed and according to reports from the Chicago Tribune, at least seven people were shot, two fatally, inside or in the parking lot of Adrianna's since 2010.
Police said the officer involved in the shooting will be on modified duty until the investigation is completed. Illinois State Police are investigating the shooting.
Markham's police chief said the officer has been with the department at least four years.