Multiple trucks have been destroyed after an explosive collision at a rest stop near Goulburn.
Police say it is a "miracle" no one was seriously injured as a result of the crash.
What's next?
The highway remains closed in both directions and a crime scene has been established.
Police say it is a "miracle" no one was seriously injured after six semi-trailers were destroyed by fire when trucks crashed into a rest area near Goulburn.
It was initially believed two trucks collided and careered into five other rigs at the Windmills Rest Area on the Hume Highway, leaving one driver missing.
But NSW Police have now confirmed just six vehicles were involved and all drivers have been accounted for.
"It is nothing short of a miracle that all six drivers managed to make it out and none of them with serious injuries either,"
NSW Police Acting Inspector Vladimir Mijok said.
Emergency services were called to the scene at Breadalbane, 30 kilometres south-west of Goulburn, just after 5am where they found multiple trucks alight.
There were reports of explosions, with a 300-metre exclusion zone put in place.
"One truck was carrying eight tonnes of butane cans, another was transporting resin, a third contained memory foam and a fourth was packed with alcohol, fuelling the resulting fire and explosions," Fire and Rescue NSW said in a statement.
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NSW Ambulance said six people were treated at the scene for minor injuries.
Two of the drivers were taken to Goulburn Hospital for mandatory testing.
Hume Highway remains closed
Rural Fire Service Southern Tablelands district manager Krystaal Hinds said more than a dozen fire trucks had been called from the wider area to attend the scene.
An exclusion zone is in place after reports of explosions and the trucks containing flammable material. (Supplied: NSW RFS)
"They were confronted with multiple trucks alight in the parking bay," Superintendent Hinds said.
"Local crews were here within 20 minutes from the time of call, so quite quick, and we've had multiple crews arriving throughout the entire morning."
Superintendent Hinds said she anticipated the road would be closed for "a while longer yet" as fire-fighting and recovery operations took place.
The Hume Highway remains closed in both directions between Gunning and Cullerin Road in Breadalbane.
Just before 11am, John Pearson from the NSW Transport Management Centre said the fire was out and the smoke was "all but gone".
"A number of trucks are parked up, heading north, so if you're expecting any trucks heading towards Goulburn, they're going to still be some time," he said.
The fiery crash occurred at the rest stop on Hume Highway 30 kilometres south-west of Goulburn. (Supplied: Google Maps)
A crime scene has been established and the Crash Investigation Unit is now on site.
"That normally does take some time," Mr Pearson said.
"All I can say is, still allow plenty of extra travel time."
Motorists are being urged to avoid the area and allow more than an hour for extra travel time on diversions through Canberra via the Federal and Barton highways.