The specially-designed buses, complete with wheelchair lifts, are a lifeline to get the children at St Christopher's to and from the school.

I just wanted to cry - I think it's so not needed. We've had a difficult year

Headteacher Maxine Grant

A criminal investigation is already underway.

Headteacher Maxine Grant said she was saddened by the mindless attack at the school which takes more than 200 children - many of whom are mentally and physically disabled - from the ages of six to 19.

The arson attack early on Sunday comes after the school was flooded earlier in the year.

"I just wanted to cry - I think it's so not needed. We've had a difficult year."

"We were thinking we'd be able to relax- the summer was upon us and the children could go out on trips and things.

"And then you come round the corner, and see all the buses burnt like this."

"It just seems such a waste," she said.

Four of the buses were completely destroyed

As well as transporting pupils to school, the buses are used for other activities for swimming lessons, horse riding lessons.

"So all these sort of things are going to have to be well thought out."

Three of the school's fleet of buses escaped the blaze - one of them was off the site at the time.

Rocco de Parno, the father of one 13-year-old autistic pupil Gino, is also actively involved in school activities, including driving the minibuses.

He said the buses were a lifeline.

"Well, they're used for everything.

"We've only got one minibus left - and we might as well park it up because it's going to upset the rest of them, because if one's going out in a minibus, they want to know why they can't go out."

There's evidence of breaking in to some of the minibuses and also the way the fire has developed suggests it was started inside the cabs of possibly two minibuses - possibly more

Fire Officer Ernie Williams

Ernie Williams, the fire officer in charge of the investigation, said there was no doubt that it was an arson attack.

"There's evidence of breaking into some of the minibuses and also the way the fire has developed suggests it was started inside the cabs of possibly two minibuses - possibly more."

There is no school for pupils at St Christopher's on Monday because it is a training day.

But Mr De Parno said on Tuesday parents and staff will have trouble explaining to the children what has happened