Russell firefighters hooked up their hoses to a hydrant opposite the station and ran them down the hill to the school, where two pre-fabricated classrooms and storage rooms were on fire.
The flames had also started spreading to the rear of the main building.
Beer said firefighters were able to quickly cut off and contain the fire, but making sure it was fully extinguished took until 10am because they had to get into the roof and wall cavities.
The blaze was fought by two Russell crews backed up two more from Paihia, who arrived on the first ferry from Opua, and one from Rawhiti Rural Fire Brigade.
After receiving information from a witness Beer also called in police and a specialist fire investigator.
Two detectives were going door to door yesterday taking statements.
Beer said the resource rooms and two classrooms had been significantly damaged. The rear wall of the main administration building had also been damaged.
The Russell brigade, which was young in terms of experience, had been put to the test and did a great job saving the main building.
''They worked really well. A few more minutes and the main building certainly would have been away,'' Beer said.
Detective Senior Sergeant Mark Dalzell, of Mid North police, confirmed the fire was suspicious and was being investigated.
The blaze — and the fact it was deliberately lit — has shocked the close-knit town, which is rallying around the 80-pupil Year 1-8 school to help.
Board of Trustees chairman Shane Maddren said the community response had been ''fantastic, immediate and extremely supportive''.
He also praised the local fire brigades for their hard work.
''Our community couldn't do without them,'' he said.
Parents were informed late yesterday that the school would remain closed all week. The fire-damaged classrooms will be demolished this week while the main building, which is still without water and power, will need cleaning due to smoke damage.
The school hopes to reopen on March 2.
Beer said it was the second building fire the newly re-constituted Russell brigade had fought in a week.
Around midnight the previous Saturday they had saved a house on Church St after a blaze started in a switchboard.
It was discovered when one of the eight occupants went to investigate a loud bang downstairs. It was fortunate all were awake at the time and managed to get out safely.