Alarming footage has emerged of a near-miss between a semi-trailer and a bus carrying 20 schoolchildren on a busy Sydney motorway during Thursday morning's peak.
The bus allegedly pulled out in front of the truck, which was travelling in the left-hand lane of the M5 at Hammondville, in Sydney's south-west, about 7.50am, police said.
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School bus in terrifying near miss
A truck crashes as a school bus pulls out in front of it on Sydney's M5 motorway. Vision: NSW Police Force
The truck braked heavily to avoid smashing into the bus and jack-knifed, with smoke billowing from its screeching tyres.
A plume of smoke spread across the surrounding lanes of the motorway, forcing other motorists to slow down.

Remarkably, the semi-trailer narrowly avoided hitting the back of the bus, which continued to drive along the motorway.
"The truck driver did extremely well," Chief Inspector Greg Tetley, from NSW Police, told 2GB.
"It could have been potentially fatal."
A NSW Police spokesman said passing motorists flagged down the bus driver, a 59-year-old man, and contacted police.
Police released traffic cam footage of the incident, and have appealed for drivers who saw the incident, and who had not already spoken to police, to contact them.
The truck driver received widespread praise online for averting what could have been a devastating collision.
"That poor truck driver must have seen his life and the lives of those on the bus and drivers behind him flash before his eyes," one person, Fiona, wrote on Facebook.
"Well done truck driver. I hope your nerves are holding up well."
Mitchell wrote that the truck driver had saved many lives. "Not only the children's but every family of the children's. He deserves an award. Absolutely speechless. Good on you mate."
Amelia wrote: "What an awesome truck driver, legend in my books."
Officers from the Liverpool Local Area Command have spoken to the bus driver, and an investigation has been launched.
Witnesses have been urged to contact Crime Stoppers on 1800 333 000.
