The Golden Highway remains closed in both directions at Cassilis due to a multi-vehicle crash just west of Thompsons Road.
Emergency services and traffic crews remain on site and police crash investigators are also attending.
3 people were injured with 2 airlifted to John Hunter Hospital.
Motorists are still advised to avoid the area with an alternative route available for motorists, but the diversion will add at least three and a half hours to the trip.
Motorists are urged to check live traffic for the alternative route.
There is no forecast for when the highway will reopen.
