Police have taken over the investigation of a fire which destroyed seven classrooms at Glendowie Primary School, in Auckland.
The fire service and police are treating the blaze, which began just after 8.30pm on Friday, as arson.
Fire Safety Investigator Ray Coleman said on Saturday afternoon that all hot-spots had been put out and fire officers had left the scene.
He said based on CCTV footage and other evidence, they've been able to conclude the fire was deliberately lit.
Police are investigating the arson, and were gathering statements on Saturday.
The flames burned through a two-floor classroom block at the back of the school.
One witness says she saw a huge black cloud, then flames metres high, followed by ashes falling everywhere.
Barbara and John Irwin, who live nearby, say the building burned almost to ground level.
About 20 fire engines and 80 fire personnel took more than two hours to bring the fire under control on Friday evening, and streets nearby were cordoned off for a time.
Fire safety officer Ray Coleman says earthmoving equipment removed roofing iron on Saturday, opening up the scene for investigators.
Children and parents visited the site on Saturday. Parent Tory Hollanby said the fire was an especially cruel blow given the community had helped raise funds for the two-storey classroom block which is now destroyed.
The school's chair, Dawn Garbett, says it is clear there's been a lot of damage, but she is confident the Ministry of Education will do everything it can to ensure that students are not disadvantaged.
The ministry has issued a statement saying it is providing full support to the school, and will work to ensure it has the classroom space necessary to open for the start of the school year.