Police are hunting a gang of children who “ambushed” a bus driver and pelted him with pre-prepared snowballs.
The youngsters, aged in their early teens, flagged the driver of the packed bus down at 8pm on Friday.
As it pulled over they got on and pelted the driver with balls which they had hidden away on their person.
Sources said the driver was temporarily deafened as he got snow in his ears.
He was so shaken he could not continue with his shift.
Inspector Lee Lyons, of Sussex Police, said officers wanted the three people responsible for tormenting the driver of the bus in London Road, St Leonards, to come forward.
Insp Lyons said: “The bus had a number of passengers on it and the bus driver was understandably very shaken.
“He was so shaken he did not feel able to continue his journey.
“It might seem like a joke but this man was driving a bus which had passengers on it in treacherous conditions.
“Jumping on and throwing snowballs at him was dangerous and that is why we are investigating it.
“It could have led to the bus going off the road.”
He said the force had received calls about snowball throwing.
A woman in Copthorne, near Crawley, contacted officers yesterday to report a group of teenage boys throwing snowballs at cars.
She said: “It is dangerous enough already.”