Christiansen said students were out of their classes for about an hour and a half as a result of the fire.
"It was well contained and extinguished by the local fire brigades," he said.
Waipukurau chief fire office Glen Millar said the fire was extinguished within 20 minutes, but due to the incident's potential for damage, a second alarm was called and appliances from Waipawa, Otane and Hastings were called, with more on standby.
"A structure fire in a large building is a huge risk, not only to the structure, which would be a huge loss to the community, but to the students and firefighters.
"We already have plans in place for certain buildings and we know how we are going to deploy. We train for it and then follow the plan. Which obviously worked.
"While the drama room was filled with smoke and the hall was also very smoky, there was minimal damage and the school was able to return to class after an hour and a half. The students had evacuated very efficiently and followed orders."
The cause of the fire is being investigated by FENZ.