One driver has been killed and another is fighting for life in hospital after being freed in a near-seven-hour operation to pull apart the wreckage from a two-truck crash on a major highway.

Emergency services were called to the Hume Highway at Oolong, north of Canberra, early on Thursday after a B-double truck crashed into the rear of another that had already left the road and rolled.

The driver of the rolled truck was pronounced dead at the scene.

Firefighters used hydraulic tools to cut the other driver free, while heavy haulage tow-trucks moved loads to give them better access during a complex rescue operation that took almost seven hours.

The driver was freed about 8.15am on Thursday. He was treated by paramedics and a specialist trauma doctor before being flown to hospital in a critical condition.

Southbound lanes of the highway remained closed at 11.30am as police investigated the scene, with traffic diverted via the Federal and Barton highways.

Police were expected to provide an update on the investigation on Thursday afternoon.

The truck driver killed in the crash was the 34th death on NSW roads in 2025.

-AAP