The shooting happened around 3 p.m. in the 3100 block of South St. Louis Avenue in Little Village, Chicago police said.
The victims, men aged 35, 39 and 42, were in a parking lot when they were shot by an armed offender who had approached in an unknown vehicle, police said.
The 35-year-old man was shot multiple times and was taken to Mt. Sinai Hospital in critical condition. The two other men were taken to the same hospital in fair condition.
No arrests have been made as Chicago police continue to investigate.
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