Four people have died in a major head on crash on the Barton Hwy in Jeir north of Canberra early this morning.

Just before 7am, ACT and NSW Emergency Services responded to a motor vehicle crash on the Barton Highway near the intersection of Casuarina Lane.

Upon arrival, they found that a Ford Ranger utility and a Mitsubishi Triton utility had collided.

The driver, a 52-year-old woman, and the front passenger, a 54-year-old man, travelling in the Mitsubishi died at the scene.

The driver and a rear passenger of the Ford Ranger – all men believed to be aged in their 20s – also died at the scene.

Another man who was in the Ford Ranger was trapped for several hours and was treated and transported to hospital in a critical condition.

A crime scene was established, and investigations are underway into the circumstances surrounding the crash.

As inquiries continue, anyone with dashcam vision or further information is urged to contact Crime Stoppers on 1800 333 000.