Arsonists set fire to Balgownie Public School and marked buildings with at least 70 graffiti tags in a vandalism spree on Tuesday night.
Students arrived at the school yesterday morning to find part of the main building blackened from a fire set in a storage area under a stairwell about 12.30am.
The fire damaged recyclable material and sports equipment before three fire crews extinguished the blaze.
Broken police tape lined the scene as Department of Education officers assessed the damage, estimated to be up to $10,000.
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Two weeks of destruction across the Illawarra The repair bill included the clean-up of approximately 70 graffiti tags drawn in black marker pen on five buildings.
The school moved swiftly to remove the tags, with many gone by recess yesterday.
Police were searching for three teenagers believed to be responsible for the malicious damage.
Wollongong duty officer Chief Inspector Ken McDonald said three people were seen vandalising the school.
He described two as males aged 15 to 16 years old, wearing black pants and black hooded jumpers.
The third suspect was described as a female aged about 16 years old, about 170cm tall with shoulder length, black hair.
She was last seen wearing a black beanie and a camouflage jacket.
It is not the first time the school has been set on fire. About two years ago, a smaller fire was lit in the school by vandals but no one was caught.
A Department of Education spokesman issued a statement saying: ``No classes have been affected by this incident and the department will be assessing the damage today. A security guard has been placed at the school.''
A resident near the school posted a comment on the Mercury's website yesterday saying the vandals may have continued their crime spree as they left the school. The reader said bins were overturned near the school and several houses had their fences kicked in.