A teenage boy is fighting for his life and five others have been injured in a crash on the Caranarvon Highway between St George and Surat overnight.

The group, all from the St George and Harlaxton area was travelling southbound on the Carnarvon Highway, 55 kilometres south of Surat when their Toyota LandCruiser came off the road shortly before 6pm on Sunday.

The teenage boy was flown to Brisbane's Lady Cilento Childrens Hospital in a critical condition with a head injury, while the 31-year-old female driver was also flown to Brisbane, for treatment at the Princess Alexandra Hospital for head, neck and arm injuries.

A 16-year-old girl, 17-year-old boy, 18-year-old woman and a 43-year-old man were also injured and were all taken to St George Hospital with minor injuries.