The Golden Highway is closed in both directions 10km south of Merriwa after an accident this afternoon.
Emergency services were called to the highway just after 2pm following reports a truck and car had collided.
The male truck driver is uninjured and is assisting police with their inquiries, he will be taken for mandatory testing.
But the 22-year-old female driver of the vehicle was trapped for a considerable amount of time.
The Westpac Rescue Helicopter is on the scene and is about to airlift the woman to the John Hunter Hospital as she is suffering from multiple serious injuries.
There is fuel and grain across both lanes of the highway and the Hunter Valley Police District estimate the highway could be closed for the next four hours at least, possibly longer.
There are diversions in place - westbound light vehicles diversions via Denman Road through Muswellbrook, New England Highway through Scone, then Scone to Merriwa Road. Eastbound is the reverse. Heavy vehicles are being parked.
Image credit: Grant Broadcasters