The 23-year-old woman was sitting in a parked car around 2 a.m. when four men got out of a black sedan and one of them tried to get into her car while flashing a handgun in the 1300 block of East 89th Street, police said.
The concealed carry holder shot the gunman once in the head, police said. The gunman ran from the vehicle and one of the people he was with started shooting at the woman, striking her once in the arm, police said.
The gunman who was shot was transported by paramedics to the University of Chicago Medical Center where he was listed in critical condition, police said.
The woman was taken to Trinity Hospital where she was listed in fair condition.
The three other suspects fled the scene and are not in custody.
Area Two detectives are investigating.