Police have praised the quick actions of a truck driver who prevented what could have been a "catastrophic" collision with a school bus in Sydney.
Frightening footage released by police shows the bus - carrying 15 students - pulling onto the M5 into the path of the semi-trailer after 7.30am on Thursday.
The truck driver jumped on the brakes with his semi jackknifing and skidding to a halt in a plume of white smoke. The bus continued down the motorway.
"I have no doubt the truck driver's actions have prevented what could have been a catastrophic motor-vehicle accident," Detective Inspector Dean Johnstone told AAP on Friday.
"It was remarkable, given the way the truck ended up, there were no other collisions.
"No one's injured, everyone's gone about their daily lives today. It's just unbelievable."
Det Insp Johnstone said the truck driver had been traumatised by the event but "showing full courage" returned to work on Friday.
"It's a testament to the character of the bloke."
Det Insp Johnstone said drugs and alcohol were not factors in the incident.
The 59-year-old bus driver Kazem Afkhamisaddoghi apologised and said he thought he had enough time to pull out.
"Unfortunately I made a mistake ... and I am so sorry about this incident," he told the Seven Network.
The students were on an excursion from Mount St Joseph's Girls' College to an AFL gala day at West Hoxton when the incident occurred.
Det Insp Johnstone confirmed the students were not harmed.
He said dangerous driving charges will be laid against the bus driver and called on witnesses to contact police.
The bus company will offer their driver more training.
"I will really need to train him and make sure that next time he knows better," GHP Australia spokesman William Matar told Network Ten.
