Three of the boys have been referred to Police Youth Services for their part in the arsons and connected burglaries.
Head of the investigation, acting-Detective Sergeant Greg Johnson, said it was sad young people were involved in the arsons.
"It is a very serious offence carrying a hefty penalty, but it is also such a danger to human life. Not only are they putting their own lives in jeopardy - they are risking the lives of their own whanau and community who turn out as volunteer firefighters."
Mr Johnson said inquiries into the fires would continue this week.
"The most important thing for us has been stopping this behaviour before someone gets seriously hurt. We and the fire service will be taking a prevention approach with these kids and their families, making sure this doesn't happen again."
- nzherald.co.nz