Three people were fighting around 10:53 p.m. in the 6000 block of North Winthrop Avenue when one of them pulled out a gun and started shooting, police said.
A 45-year-old man was struck in the chest and was taken to Saint Francis Hospital where he was listed in critical condition, police said.
Another man, 34, was shot in the leg and was also taken to Saint Francis Hospital. He was listed in good condition.
No one is in custody as Area Three detectives investigate.