Nichole Rodriguez, 28, was gunned down sitting in the passenger's seat of the car in a Joliet driveway just after midnight, reportedly hit twice in the torso. Joliet firefighters brought Rodriguez to Silver Cross Hospital where she was pronounced dead at 12:56 a.m.
Police are searching for two men who reportedly approached her car and opened fire.
The girl and the woman's 20-year-old stepsister, who was also in the car at the time of the shooting, were uninjured.
The Associated Press contributed to this report.