The road was closed after her vehicle left the roadway just south of Mullion Creek, around 20 kilometres from Orange.

Central West Police District Inspector Dave Harvey said the vehicle, which was heading north, left the road about 9.45am on Tuesday.

"A bus-type campervan has left the road and hit a tree for unknown reasons," Inspector Harvey said.

The woman, 69, from Victoria, died at the scene.

Inspector Harvey and a NSW Ambulance spokesperson confirmed only one person was in the vehicle.

A Toll helicopter was also called to the scene along with four ambulance crews.

The incident occurred near the intersection of Fanning Road and Burrendong Way.

Diversions are still in place as of 1pm Tuesday and the public is urged to avoid the area if possible.

NSW Ambulance station officer Melissa Parker said it was sad to see.

"These types of accidents are dreadful for everyone involved," she said

"We urge everyone to take extra care on the roads. One small mistake can lead to serious injury.

"Our hearts go out to the patients family and friends."