The blaze was reported after 10:30 a.m. Saturday at the school in the unit block of Walt Road in Red Hill.
The fire has been ruled accidental, with investigators saying the flames were sparked by some type of electrical or mechanical failure that happened on top of a wooden cabinet in the tech ed room.
Firefighters arrived to find fire showing from the exterior of the building. They were able to control the flames and get the situation under control within an hour.
But Action News is told smoke from the blaze got into the school's ventilation system and spread to classrooms throughout the building before crews were able to douse the flames.
As a result, the fire marshal determined the building will remain closed Monday so clean up work can continue.
Action News has confirmed that two off-duty firefighters were taken to area hospitals in stable condition to be treated for hand injuries.
We are told the fire caused significant damage to a rear section of building near the horticulture area.
Send a News Tip to Action News
Learn More About 6abc Apps