Thieves in Christchurch are stealing outdoor speakers that schools rely on in emergencies.
Four schools in the city have been targeted, the latest being Saint Albans Primary School, which has been hit five times in the last four weeks.
Security footage shows one would-be thief hoisting the other up to a speaker outside the school, under the cover of darkness.
When that fails, he climbs onto his friend's back, heaves, and rips the speaker down.
"You're stealing from kids," acting principal Claire Howison says.
"At the end of the day, you're stealing from kids."
Twenty speakers were stolen, but Ms Howison says the biggest impact is on "the safety of children".
"It's our PA system that we use in emergencies and it's our bells, and children can't hear it if the speakers aren't there."
Speakers are also disappearing from Auckland schools. It's thought they're being attached to bikes by teenagers to hold music battles.
In Christchurch, installers are working on anti-theft measures.
"We don't want to just carry on putting more and more of these speakers up, because when we have done this in the past, within a couple of days they've been stolen again," Simon Briscoe from Garden City Communications says.
St Albans Primary School believes their security camera has captured four separate groups of people working over several weeks, which indicates there could be a real market for the speakers, with the thieves potentially even working to order.
Each theft is under the $1000 insurance excess, leaving schools to foot the bill.
"Every cent is required for the resourcing and materials that we need for these children. And you're taking it away from them. It's not fair," Ms Howison says.
The school is now frustrated and out of pocket - and are relying on police to catch the brazen thieves.