Carol Stream police responded about 6:45 p.m. to the area of Gary Avenue and Stark Drive for a reported crash involving a vehicle and a pedestrian.
When officers arrived, they found the woman, who was unresponsive.
She was taken to a local hospital, where she died.
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Her identity has not yet been released.
No one else was injured, police said.
The DuPage County Metropolitan Emergency Response and Investigations Team's Crash Reconstruction Team is assisting in the investigation.
Everyone involved has been identified, but the investigation is ongoing, police said.
Anyone with information should contact traffic Sgt. Greg Walker at (630)-668-2167 or gwalker@carolstream.org.