Just before 2.30pm, emergency services were called to the New England Highway, Aberdeen, following reports two vehicles had collided.

Upon arrival, emergency services located one vehicle well alight, which started a small grass fire that was extinguished a short time later.

A woman, who was a passenger, died at the scene.

NSW Ambulance paramedics also treated two men, who were the drivers, at the scene before both were airlifted to John Hunter Hospital.

A male in his 30s sustained head injuries, while a 54-year-old male also suffered multiple injuries, police said.

He was airlifted to John Hunter Hospital for specialist treatment.

Police from Hunter Valley Local Area Command with the assistance of the Crash Investigation Unit have established a crime scene and are investigating the circumstances surrounding the crash.

Major traffic delays are expected with a contra-flow currently in place.

Motorists are urged to avoid the area between Aberdeen and Muswellbrook and check www.livetraffic.com for updates.