The CFA attended received the call at 3.20am, and took over two hours to control the blaze. 

It destroyed the north wing of the school, which contained science rooms, a computer lab, teachers’ offices and a careers centre. 

CFA brigades from all over the region took part in the fight to control the fire and incident controller Alex Pearce estimated there were between 60 and 70 firefighters on scene at its peak. 

The school is now a crime scene, Moorabool CIU detectives waiting on results from the arson chemist to determine how the blaze started. 

Police told Fairfax Media they believed people broke in to the school around 3am. 

Principal Graeme Holmes said the fire had shocked the school community. 

“It's devastating for the school, the whole community,” he said.

“Just devastating for everyone. A really really sad day for the whole of Daylesford.”

Mr Holmes said they would work with the Department of Education to get students back to school on time. 

“We'll be able to restart school on schedule. (Getting students back) won't be a problem, the problem will be the lack of a science building and the lack of specialist classrooms. That will be the bit we have to work our way through,” he said. 

“We need to look later at what can be salvaged, it's highly unlikely we'll be able to salvage anything.

“We'll be able to restart school on schedule. (Getting students back) won't be a problem, the problem will be the lack of a science building and the lack of specialist classrooms. That will be the bit we have to work our way through.”

An emotional Mr Holmes said the prospect of a deliberately-lit fire made the traumatic morning even worse. 

“It's bad enough as it is, but if we find that it has been deliberately lit, that makes it even more gut-wrenching for the community and the school to think that someone would do that.”

Anyone with information can contact Crime Stoppers on 1800 333 000 or visit crimestoppersvic.com.au