THE New England Highway is closed in both directions at Camberwell, north of Singleton, due to a serious crash involving a car and a truck at Glennie Street.
Emergency crews, including a medical helicopter, were called to the site on Wednesday morning.
Traffic crews are also attending.
Motorists can divert via the Golden Highway to Denman Road at Denman to return to the New England Highway at Muswellbrook.
Motorists should also allow plenty of extra travel time.
For the latest traffic information, visit www.livetraffic.com, download the Live Traffic NSW app or phone 132 701.