Brentwood police say it happened at about 7 a.m. on Sunrise Road and Trailside Drive.
The girl was apparently walking to Edna Hill Middle School when she was hit by an SUV traveling eastbound.
Police Lt. David Schroer says the driver left the scene but was later found a short distance away in a parking lot on Elkins Way.
The driver was booked into the Contra Costa County jail on charges of felony hit and run and DUI.
The young victim is in stable condition.
Dr. Dana Eaton with Brentwood Unified Superintendent of Schools told ABC7 News that students who had class with the young victim were told about the incident and were offered counseling. He also had some advice for local drivers.
"Drive as if your own children were walking to school."