A driver has died after a fuel tanker and two other trucks collided on the M1 Pacific Motorway in the Lake Macquarie region, sparking explosions and a bushfire.

The male driver of one of the trucks died at the scene.

Southbound lanes are expected to be closed for some time with a diversion in place and northbound traffic has only one lane open with delays expected.

About 12:30pm a truck travelling southbound along the M1 "clipped the rear" of a truck parked on the side of the road causing three trucks and a car to be involved in the fiery crash, NSW Police Detective Inspector Darren Cox said.

"It has caused a large collision involving a B-double [truck] as well one carrying a fairly extensive fuel load," he said.

The truck carrying ethanol caught fire and emergency services arrived on the scene about 20 minutes after the crash.

The lone car involved was seriously damaged, but the female driver was "OK" with a number of people involved in the crash taken to hospital, Detective Inspector Cox said.

Ambulance services treated one patient for minor leg injuries.

Bushfire started from truck crash

Sorry, this video has expired Emergency services put out the fire caused by two trucks crashing on the M1

The flames sparked a bushfire, with the NSW Rural Fire Service getting the 16-hectare fire under control in the late evening.

Superintendent Greg Windeatt from Fire and Rescue NSW said the firefighters were "past the worst" mid-afternoon on Monday.

Police said the scene remained dangerous and any crash investigation would take significant time.

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Two fatalities in another regional truck crash

Meanwhile, two men were killed in a head-on crash between a pair of trucks near Grafton in north-eastern NSW.

A truck carrying cattle collided with a tipper truck at on the Gwydir Highway at Jackadgery, 40km west of Grafton.

The two truck drivers, who were both in their 50s, died at the scene.

A local vet was on scene to euthanase injured cattle from one of the trucks.