One person is dead after what appears to be a head-on collision on the Monaro Highway south of Canberra.

Key points: A head-on crash between a semi-trailer and a car has claimed one life

A head-on crash between a semi-trailer and a car has claimed one life The Monaro Highway near the Royalla Solar Farm has been closed for the rest of the day

The Monaro Highway near the Royalla Solar Farm has been closed for the rest of the day Police have provided counselling to the surviving driver, and are investigating how the crash unfolded

A car and semi-trailer collided near the Royalla Solar Farm, about five kilometres south of Johnson Drive, at about half-past nine this morning.

ACT Policing described the scene as "traumatic", and warned the highway would be closed in both directions until further notice.

The deceased driver was the only person in the vehicle, and no details of their age or gender have been released.

The driver of the semi-trailer has been spoken to by ACT Policing and ambulance officers, and is being counselled.

Detective Acting Station Sergeant Marcus Boorman said crash-scene investigators would be working throughout today to reconstruct what happened.

"We're still working through the scene, obviously it's a highway, 100km/h speed zone," he said.

"At this point it looks like the vehicles were approaching from opposite directions."

The stretch of the Monaro Highway south of Canberra has been the scene of multiple fatal crashes. ( ABC News: Isaac Nowroozi )

He said it was a complex scene, that would take plenty of time to piece together.

"Any collision where a very large vehicle is involved is very confronting," he said.

"We plead to people to pay attention, slow down and pay attention on the roads."

The Monaro Highway is a single-lane road in both directions for most of the drive between Canberra and Cooma, and has been the scene of multiple fatal accidents in recent years.

Two people were killed in an accident on the same road, north of Cooma, in late July.

Traffic builds over the winter months as it is the primary route to the New South Wales snowfields, south of Cooma.

It is the fourth fatality on ACT roads this year.