EXTRA police patrols will be mounted after violence erupted outside a school.

Three buses were ambushed as they took youngsters home from Sharples School, Sharples, on Friday afternoon.

And today police warned that anyone involved in a repeat of the violent scenes would face arrest.

Insp Tony Kenyon said: "We will not tolerate any form of violence or anti-social behaviour."

Trouble flared after a gang of youths - who were not pupils of the school - gathered outside the gates at around 3pm.

As buses were travelling along Ashworth Lane, near to the school, they were attacked by a gang throwing stones. The double-decker buses were forced to stop after windows were smashed and residents then witnessed running battles in the street.

Insp Kenyon said police were patrolling the area at the time after warnings by the school of a possible disturbance and would continue to maintain a presence over the coming days.

He added: "We are making inquiries into the background of this incident. It would appear at this stage that the disturbance was caused by a group of youths who are not from the school.

"We are working together with staff at the school and youth workers to prevent any further incidents. I would like to reassure pupils and their parents that there will be a police presence in the vicinity of the school for at least the next few days."

Kevin Clarke, headteacher of Sharples School, said: "These kinds of incidents don't normally happen at our school. We are being extra vigilant and are working with police to ensure that we don't have a repeat incident.

"We did everything we possibly could to protect our pupils on Friday. We heard rumours that their was a gang of youths who were not from our school, outside school premises.

"We had members of staff who were patrolling school grounds both inside and outside our premises.

"We contacted the police and they had a presence on school premises at break time, lunch and the end of school.

"It was a peaceful day and we did not anticipate there to be any trouble at all with pupils on the school bus.

"That is why we did not send our pupils home.

"We did everything we possibly could to avoid what happened.

"The police were at the scene in minutes.

"We have sent out letters to parents to reassure them that we are being extra vigilant.

"The children's health and safety is of paramount importance to the school."