Police were called to the 3700 block of West 139th Street in Robbins around 1:30 a.m., where they discovered a male gunshot victim.
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The victims was transported to a hospital, where he was pronounced dead, police said.
No other details surrounding the circumstances of the shooting were immediately available as police continue their investigation.
A Labor Day parade was scheduled for 2 p.m. Sunday in Robbins, and those plans will not be affected by the overnight homicide, a spokesperson said.
This story previously said the shooting sparked the southern suburb's first homicide investigation in four years based on information from a Robbins Police Department spokesperson.