The shooting happened at about 1:51 a.m. at the Dollar Tree in the 2900-Block of Colorado Avenue, police said.
A 31-year-old man was found with a gunshot wound to the head. He was rushed to St. Joseph Medical Center, where he died, police said.
The man's identity has not been released.
Police said they found a handgun in the parking lot along with multiple shell casings.
Two cars parked nearby were struck by gunfire; the vehicles were empty, police said.
Anyone with video is urged to contact Joliet police.
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