A young driver was found unconscious and seriously injured in an overturned vehicle near Crudwell this morning.
Police were called just before 10.20am with reports that a car had been seen upside down in a ditch off the Culkerton crossroads at Kemble.
An 18-year-old male driver, who is thought to be from Essex, was found in the green Volkswagen Golf, which was in a hedge.
A fire crew from Malmesbury and a second crew from Tetbury attended and the man was cut free.
The Wiltshire Air Ambulance airlifted the man to Frenchay Hospital, near Bristol.
The A429 Crudwell northbound road has been shut in both directions, and is expected to be closed for several hours.