Investigators say speed was a factor when the driver of a Nissan Sentra went over the side of Glendora Mountain Road Thursday just after midnight.
The teens, whose names have been withheld, managed to climb to the road following the crash and call for help.
Two of the teens were airlifted to a hospital in critical condition. The others were transported to the hospital with moderate injuries.
Fire officials say the area is known for street racing.