The child was hit near the intersection of Algonquin Road and Thoreau Drive, police said.
The girl was taken to a nearby hospital for life-threatening injuries, but later died, police said.
The girl has been identified to the Cook County medical Examiner's Office as Angela Guan.
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Schaumburg police are investigating the fatal crash.
It was not immediately clear what led up to the incident, or who else was involved.