An earlier notice informed the school community that classrooms one to four were all on fire.
"Please stay away until further notice."
A parent at the scene told the Star News that they had been told the fire was near the office building.
"We just saw a big cloud of smoke across from the direction of the school. I am just so pleased it didn't happen during school hours."
The school's deputy principal, Jane Rush, told the publication the fire was "substantial" and that school management are due to be in touch with the appropriate authorities.
"The classes damaged were senior classes," she said.
"At this stage, the school is closed and we will be discussing how long it will be closed with the Ministry of Education today."