The fire was discovered just before midnight and 40 firefighters spent five hours putting it out.
Fire and Emergency shift manager Paul Redden said the top floor of a two-storey block was on fire when crews arrived.
The fire is now out and a fire investigator will be at the school this morning to determine the cause.
In a third incident in the last 12 hours a Tokoroa man was flown by rescue helicopter to Waikato Hospital after he was rescued, unconscious, from his smoke-logged home on John St at 7.45pm.
He was in a critical condition last night.
A dog found unconscious in the house was also given oxygen at the scene.