This is the shocking moment schoolchildren watch on as what is thought to be their bus driver has a roadside brawl.

The video, filmed on Tuesday afternoon, shows the driver getting punched by another motorist.

It is believed the extraordinary scenes came when the pair swapped insults after a driving incident. 

The 33-second clip shows Thorpe St Andrew High pupils watching on in amazement as the driver - believed to be in blue and called Ken - is thumped by another motorist. 

Norwich Evening News: A still from the videoA still from the video (Image: Supplied)Norwich Evening News: A still from the videoA still from the video (Image: Supplied)

At one point, the bus driver pins the man to the floor before pleading with his attacker: "I've got a bus full kids." 

The children can be heard laughing and egging on the bus driver shouting "they're having a scrap", "he's going to get the sack" and "oh my god, Ken's got him".

Norwich Evening News: A still from the videoA still from the video (Image: Supplied)

Norwich Evening News: A still from the videoA still from the video (Image: Supplied)

One boy even screams: "To be fair the other guy did pull out in front of him."

A Thorpe St Andrew High School spokeswoman confirmed the incident had been reported to police and clarified that the bus driver was not employed by the school. 

Norwich Evening News: A still from the videoA still from the video (Image: Supplied)

Norwich Evening News: A still from the videoA still from the video (Image: Supplied)

The spokeswoman said the bus driver is employed by a company contracted by Norfolk County Council.

A spokeswoman for Norfolk County Council said: “We are aware of an incident involving a school transport operator today. We are investigating with the operator and will deal with the incident appropriately."

The police have been approached for comment.