The Barrier Highway, west of Cobar has been closed to traffic after a fatal accident this morning.

A 14-year-old boy is reported to have died after the car he was travelling in rolled over near Cubba, 25km west of Cobar.

Emergency services were called to the site shortly after 8:30am. The boy, who died at the scene, was one of four passengers in the vehicle.

The driver, a 23-year-old woman, was not injured. She was arrested and taken to hospital for mandatory testing.

Two other passengers were not injured.

Police have established a crime scene and have begun investigations into the cause of the crash.

The Barrier Hwy was closed in both directions at Cubba, between Kidman Way and the Cobb Hwy.

Traffic diversions were in place and drivers have been advised to delay their travel until the highway reopens.

A report will be prepared for the coroner.

Anyone with any information or dashcam footage has been urged to contact Crime Stoppers.