Emergency crews have rushed to Bulli Pass after reports of a truck overturned and well alight.
It is understood the vehicle crashed into multiple power poles before hitting a concrete barrier, flipping onto its side and coming to a halt on a parked car on the opposite side of the road. It then burst into flames, witnesses said.
A police officer escorted the driver away from the vehicle, down the Pass, according to reports.
Southbound and northbound lanes are closed and motorists should consider exiting the M1 at Lawrence Hargrave Dr.
Northbound traffic is banked back to Bulli Public School.
Traffic authorities recommend avoiding the area.
Kerry Davenport saw the accident happen in his rear-view mirror.
"I was coming down Bulli Pass and this truck came behind me out of nowhere - it was flying, it looked like it had no brakes whatsoever," he said.
"I could see it all in my mirror - the truck hit a pole, took out a car and a few more power poles and then crashed through the concrete barrier in the middle of the road and across to the other side and burst into flames.
"It's made a right mess - if that concrete barrier hadn't been there it would have gone through some houses."
Mr Davenport said the truck driver was able to escape the wreckage.
Both directions are expected to remain closed until later this evening. A complex salvage operation will be needed along with repairs to power poles and wires. Avoid the area and use the M1 Princes Motorway or Lawrence Hargrave Drive instead.