Emergency services have been called to reports of a truck crash in the Upper Hunter.
First reports say a B-Double ran off the Golden Highway about 5 to 10 kilometres south of Merriwa just before 5.00am on Tuesday.
It appears the semi may have swerved off the road before ending up sideways across the highway.
Police say the semi is leaking fuel and the highway is blocked in both directions.
Firefighters have arrived at the scene and have requested an ambulance for the truck driver who they say appears to have suffered minor injuries.
