Road users are urged to avoid the A47 near King's Lynn, following a serious accident which has closed the road in both directions at Walpole Highway for several hours.
Police were called at 5.53pm on Monday to reports of a single vehicle crash on the A47 westbound carriageway.
Emergency services, including fire and ambulance, were sent to the scene.
The vehicle collided with the central reservation prompting the road to be closed and diversions put in place.
The air ambulance took the male driver and only occupant of the vehicle to Addenbrooke's in Cambridge for treatment.
There is still no confirmation of when the road will reopen.
Road users should avoid the area for the next few hours, while the road is cleared of debris, and repairs are carried out to the central reservation barriers.
Any witnesses to the collision should contact Norfolk Constabulary on 1010.
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