A sedan and a four-wheel drive collided head-on on the Princes Highway at Jerrawangala about 5.20am on Friday, police said.

Both drivers, a man and a woman, died at the scene.

Vision from the aftermath of the crash shows the four-wheel drive spun off the road, and the front of the sedan was completely crumpled after the impact.

The cars appear to have collided at a curved section of the highway.

Police say the man and woman were the sole occupants of the vehicles.

Inspector Ray Stynes from Nowra Police Station said the Princes Highway would likely remain closed in both directions until mid-morning.

"We make a plea to drivers that they drive to the conditions of the roadway," he said.

"Adhere to the speed limit and just be careful of driving particularly in the early hours of the morning."

Inspector Stynes said the cause of the crash was yet to be determined.

"Once the investigations have been completed a report will be prepared for the coroner," he said.

In a separate fatal crash on Friday morning, a truck driver died in a crash on the Pacific Highway near Port Macquarie.

A semi-trailer, believed to be travelling north, off the road at Herrons Creek about 3.30am before it rolled and burst into flames.

The driver was trapped in the truck and died at the scene.

In the state's south-west, an 18-year-old man died after crashing off Muttama Road near Cootamundra about 12.15am on Friday.

The man's car left the road and hit a tree before it caught fire. Emergency services were called but the driver and sole occupant of the car died at the scene.

Deadly crashes on the Princes Highway

Friday's double fatality at Jerrawangala happened about 15 kilometres north of the site of fiery Boxing Day crash at Bendalong, in which four members of the Falkholt family died.

Lars and Vivian Falkholt and their two daughters, Annabelle and actress Jessica, were driving in their family car when it was struck head-on by another vehicle on the Princes Highway.

Mr and Mrs Falkholt died at the scene along with Craig Anthony Whitall, who had been driving the other car.

The sisters were pulled from the wreckage before the car burst into flames and flown to hospital.

Annabelle, 21, died three days after the crash, while Jessica, 29, was taken off life support the day after her family's funeral and died six days later.