Rosemont police said an "isolated and targeted" shooting took place near the food court inside Fashion Outlets of Chicago just after 7 p.m.
WATCH | Witnesses describe running for cover as shots fired inside mall
Two shooting victims were rushed to local hospitals and were initially reported to be in critical condition.
Police said one of the shooting victims, a man in his 20s, died at the hospital. His name has not yet been released.
A 15-year-old girl was also shot in the wrist, police said. Her condition has since stabilized.
Police said there may have been a third shooting victim who left the area.
Witnesses inside the mall said they heard three to five shots fired and saw people rushing for the exit.
"We heard four gunshots rapidly and within minutes, we just ran," Gucci store employee Maria Salgado said.
"I noticed that a stroller was ah, had fell over, and it was a kid's bottle laid out next to the stroller, it was a little girl's stroller," witness Stringer Harris said. "And that just told me how serious this matter was. As far as, like, it goes from zero to 60 just that quick. You know, you're walking down with your family having a good time and shots go off."
Police said the area is now safe, but Rosemont officers were going from store to store to get shoppers and employees out.
Police said people can reunite with their loved ones at the nearby Caddyshack restaurant.
Police said the suspects fled the scene in a red vehicle. So far, no one is in custody.