No charges had been laid as of last night.
The driver was located by police and was still being questioned late yesterday.
Tauraroa Area School principal Grant Burns said a staff member and parents were at the scene after the accident. He said staff and students were concerned about the incident.
"We've had counsellors at the school who've been active supporting friends of the injured student and are certainly putting every care into their work," Mr Burns said. "Our main concern obviously is with her family, but we've got to take care of other students and anybody else affected by all this."
The accident happened about 10km from the school. The car was heading north. Mr Burns said the girl was on her way home.
A number of serious crashes have occurred on that stretch of road in recent years, including one in January when a holidaymaker allegedly fell asleep at the wheel, drifted over two lanes and rammed into a tree.
That driver walked away with no injuries, but the passenger in the car needed treatment for moderate injuries.
The number of crashes in Oakleigh has decreased since major roadworks were carried out in 2011 to widen the road and bridge, to create right-hand turns into the service station and Springfield Rd.
The hit-and-run was one of three accidents involving children hit by vehicles in 24 hours.
A 2-year-old died after he was hit by a car in a KFC carpark in Napier yesterday, and a girl hit by a truck in central Ashburton on Wednesday was in a serious but stable condition in Christchurch Hospital. The girl, 11, was hit while crossing SH1 about 4.45pm.
