A man has died and another driver remains missing after a devastating head-on collision on the Monaro Highway in southern NSW in the early hours of Sunday morning.

Emergency services were called to the stretch of highway at Colinton, in the Snowy Mountains region, about 12.15am following reports that two vehicles had collided head-on. The crash occurred under darkness on a quiet section of road, turning a routine overnight drive into a tragic scene.

When police and paramedics arrived, they found one of the drivers had died at the scene. Despite efforts from emergency crews, the person could not be revived. The identity of the deceased has not yet been formally released, pending notification of next of kin.

In a troubling development, the driver of the second vehicle involved in the crash has not been located. Authorities have not confirmed whether the individual left the scene before emergency services arrived or was unable to be found in the immediate aftermath due to the severity of the collision. The unexplained absence has added a layer of uncertainty to an already heartbreaking incident.

A crime scene has been established as specialist officers examine the wreckage and surrounding area. Investigators are working to piece together the moments leading up to the collision, including the speed and direction of travel of both vehicles. Forensic teams have been combing through debris and skid marks on the roadway, hoping to determine exactly how the crash unfolded just after midnight.

As of Sunday afternoon, the Monaro Highway remains closed in both directions between Old Cooma Road and Yareen Road. Traffic diversions are in place, and motorists are being urged to avoid the area, delay any non-essential travel and seek alternative routes. The closure has caused significant disruption for drivers travelling through the Snowy Mountains region.

Police are appealing to the public for assistance as the investigation continues. Anyone who was travelling along the Monaro Highway around the time of the crash, particularly those with dashcam footage, is urged to come forward. Even the smallest detail, officers say, could prove crucial in establishing what happened in the lead-up to the fatal impact.

Information can be provided to Crime Stoppers NSW anonymously. Authorities are determined to uncover the full circumstances behind the crash as a community grapples with the shock of a life lost and another person still unaccounted for.