Police said the crash happened just before 7:45 a.m. in the West Englewood neighborhood's 1700-block of West 69th Street.
Police said two girls, 6 and 15, were in a crosswalk when a white SUV hit them.
Both girls were transported to Comer Children's Hospital, with the 6-year-old in critical condition and the 15-year-old in serious condition.
On Saturday, police said they are looking for a white and black 2010 Lincoln MKT with an Illinois license plate reading FS73498.
The vehicle may be damaged on the front, hood or windshield and has a sticker on the left side of the rear window, police said.
CPD's Major Accidents Unit is investigating. Police asked anyone with information to call them at 312-745-4521 or submit an anonymous tip at CPDTIP.com and use reference #JK-156072.
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