The fire was noticed by nearby residents who called triple-0 at around 1.05pm.

Fire and Rescue in Nowra sent two crews, while Rural Fire Service units from St Georges Basin, Basin View, Sanctuary Point and Huskisson brigades also attended the fire, but it was well alight.

Well over an hour later flames were still visible inside the building and smoke poured from the roof as crews still worked on extinguishing the fire.

The building on the northern side of the school near adjoining bushland housed 120 children from years 3 and 4 and two combined classes of year 3/4 and 4/5.

Year 3 teacher Jennifer Brown was horrified as she saw the ruined computers and smart boards in the burnt out classrooms and buckled roof of the building in which she taught.

“Some neighbours called to say someone was burning off at the school, but when I got here it was absolutely terrible,” she said.

“I was shaking, it’s really horrible.

“We’ve had vandalism before, but nothing like this.”

Rural Fire Service spokesman James Morris said he couldn’t confirm the cause of the fire but police and RFS officers were investigating.

Tracy Mandavy from the school’s Parents and Citizens group said she was “devastated” by the news.

“The kids have worked so hard on their artwork and now it’s gone,” she said.

The school’s principal Kathy Rembisz was returning from a holiday last night and would make a decision about the future of the building and the students today, said Ms Mandavy.

However it is unlikely the building will be usuable in the foreseeable future

“The whole building is not safe to enter. The eaves have burnt and it’s not structurally sound – the kids won’t be safe,” said Mr Morris.

Another fire over the long weekend burned 14 hectares around Bomaderry Creek walking track.

Station Commander Mick Adams of Nowra Fire and Rescue said the blaze which began at 5.15pm on Friday wasn’t extinguished until 8.50am the following morning.

Nowra Fire and Rescue attended five fires last Thursday – three at Narang Road in Bomaderry and grass fires in Scenic Road, Nowra and Old Southern Road, South Nowra.