Newly installed pou at Whangaparaoa College have been vandalised, putting their unveiling on hold.
Police were investigating after plastic covering the carvings was set alight on Monday night.
The carvings, which were designed and made by prisoners at Nga Wha, were due to be unveiled in a ceremony at the school today.
Whangaparaoa College principal James Thomas believed the act was not sinister, but instead an immature and stupid act.
He was concerned for the culprits, who had broken tapu, and hoped if they were found they could enter a restorative programme so it never happened in the community again.
Mr Thomas said the school was still figuring out how the pou would be restored.