Bus drivers said the students were tired, hot and grumpy from having to sit for so long.
The accident occurred about 3:30 p.m. when the driver, Barbara Jean Wilt, 41, of Halltown, W.Va., was heading east on W.Va. 9 with another woman in the front passenger seat, said Trooper D.D. Forman.
Witnesses said the Colt Vista went around a curve and then ran off the road onto a narrow gravel shoulder, Forman said.
The vehicle struck a pile of rock and brick debris in a ditch and went airborne briefly before hitting the concrete head-on, Forman said.
The concrete culvert allows a mountain spring to run under the road.
The front end of the car wrapped around the culvert, pushing the dash board onto the legs of the passenger, Knill said.
About 20 firefighters and medics from Blue Ridge Mountain and Independent fire companies arrived at the scene.
The top of the vehicle was cut off by rescuers and the driver was freed immediately.
Medics had to work to stabilize the passenger's injuries and then cut her free from the wreckage. She was taken by ambulance to a nearby landing zone, from where a helicopter flew her to Fairfax Hospital in Virginia. Her condition was unavailable Wednesday night.
Wilt was treated at Jefferson Memorial Hospital and released, said hospital spokeswoman Teresa McCabe.