It was a very lucky escape for drivers after a truck veered onto the other side of a busy motorway in Ryde in Sydney's North West.
In alarming dash-cam footage obtained by Nine News Sydney, the truck almost struck several cars and another truck before coming to a halt inside of a tunnel overpass.
The incident involved at least three other cars was reportedly caused after the driver "blacked out" while behind the wheel.
A number of bystanders have been praised for attending to the truck driver.
"Good to see we are good-natured humans...and the 2 big trucks blocking to make it safe. Hope hes ok and the red Prado driver too," wrote one on the Dash Cam Owners Australia Facebook page.
Another said: "Well handled everyone! Obvious that something was up with the truck driver. Everyone got the hazards on, hopped out and assisting well done."
You can watch the footage from the incident below: