Deputies say the incident happened around 2:50 a.m. in the 11500 block of Huffmeister.
According to the sheriff's office, the child's mom had reported her daughter, who she said has autism, had left the house.
WATCH: Harris County Sgt. Simon Cheng provides details on child with autism hit by car
Harris County deputies update on 8-year-old with autism hit by vehicle
The child reportedly wandered into the street and was hit by a Nissan Murano that was traveling north on Huffmeister. The driver of the vehicle, a 49-year-old woman, stopped immediately and called 911.
The driver did not show signs of impairment and is cooperating with authorities.
Authorities say the 8-year-old suffered critical injuries and was taken by LifeFlight to the hospital, where she is currently in surgery.
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