Vandalism against public schools has cost ACT taxpayers more than $1 million over the past four years, government figures reveal.
While incidents have fallen in the past decade with the roll-out of more high-security fences around campuses, this year looks on track for another large clean-up bill.
Twenty-nine incidents were reported in just the first three months of 2019, more than a third of the total recorded last year.
The figures come as police hunt for three vandals who attacked a Catholic school in Gungahlin over the weekend.
Staff at St John Paul II College said they were devastated by Saturday's vandalism, which was caught on camera.
Footage shows one of the vandals throwing large rocks at sliding glass doors and windows just before 8.30pm.
Security cameras were also damaged with spray paint.
Principal Catherine Rey said the damage to the doors and windows alone was estimated at $6000
"There's been almost no vandalism in the last six years, this was quite distressing," Ms Rey said.
"It was clearly malicious that these big rocks were brought in from somewhere else. It took them about four goes to break the main front door down."
After uploading the footage to social media, staff said they had passed on leads to police.
No arrests had been made as of Thursday, police said.
Canberra's Catholic Education Office said vandalism attempts on Catholic schools happened from time to time but did not appear to be increasing.
The archdiocese does not keep data on incident numbers or costs.
The ACT education directorate said it worked closely with police and schools on security measures.
At last count, 69 of the ACT's 87 public schools had installed high perimeter fences.
Last year, there were 85 reports of vandalism against public schools, costing $294,721 in total.
That was up from 62 incidents each in 2017 and 2016 but down from 300 attacks in 2009.
"Unfortunately...vandalism remains a reality the government and schools need to manage," a directorate spokesman said.
Incidents could lead to unscheduled disruptions for schools, he said, urging the community to view public schools as community assets to be proud of. When a school didn't have enough in its budget to cover vandalism repairs, the directorate would pitch in extra funding, the spokesman said.
This year's summer holidays were marred by a spate of vandalism at north-side schools, including at Gold Creek Primary where a tractor was used in a destructive rampage across the oval.
In the ACT assembly on Thursday, Education Minister Yvette Berry said the government worked closely with school communities following vandalism incidents.
"If there's significant damage then the [directorate] will go in very quickly and support the schools to resolve issues,"she said.