State police are still investigating the cause but it was a two-vehicle accident near 75th Street. A 6-year-old boy is in critical condition, and a 3-year-old girl and a 4-year-old girl are in good condition.
Two other adults were taken to University of Chicago Hospital in serious but "stable" condition, according to Fire Media Affairs spokesman Will Knight.
The accident reportedly backed up traffic on the outbound Dan Ryan for hours during this Monday evening's busy holiday rush.
The Sun-Times Media Wire contributed to this report.