About 5.30am on Wednesday, emergency services were called to the Mitchell Highway, about 30km west of Nyngan, after a vehicle left the road and crashed into a tree.

The female driver died at the scene, police said at 10.30am.

Three passengers were treated by NSW Ambulance paramedics for various injuries.

They have been airlifted to Westmead Hospital in various conditions, police said.

Officers attached to Central North Police District established a crime scene, which is still being examined.

An investigation into the circumstances surrounding the crash is under way.

As inquiries continue, police are appealing to any witnesses to the crash or anyone who might have dashcam footage to come forward.

Road closures are in place. For the latest traffic information visit www.livetraffic.com.

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