It took three hours for crews to extinguish the fire at the old St. Francis Xavier’s Primary School campus.
Firefighters also put out several grass fires nearby and came across a car that had been torched while returning to the station.
Police believe the fires were started by an arsonist and Hunter Valley Police District officers have established a crime scene that will be forensically examined.
Anyone with information is urged to call Crime Stoppers on 1800 333 000.
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