The highway was closed in both directions after the collision, which left the girl and the female driver with major injuries, according to the California Highway Patrol.
The wreck caused the closure to be in place from Tierra Rejada Road to Somis. Another closure was reported at Balcom Canyon and Stockton Road, according to the CHP.
The 118 remained closed in both directions Friday evening as crews worked to offload 2,000 gallons of gasoline that spilled from the overturned tanker, officials said.
It's unclear what caused the wreck.