Police arrived yesterday afternoon and took away the two boys, who were aged around 15 and 16, she said.
The youths told her there was a fire on the playground overnight.
Firefighters were called out to the address at 5.42am to put out the fire, which damaged about 30 per cent of the structure, station officer Aaron Summerhays said.
Bell St resident June Mariner was at home in the morning when her husband, who was leaving for work, came back to the front door and told her to call the fire service.
The building was burgled as well, about three months ago, she said.
Now with the fire damage, smashed windows, and other damage to the building, Aroha didn't know what they would be doing with it.
She didn't know how much it would cost to fix everything, but the glazier was coming soon to board up the windows.
The ceiling lights inside had also been smashed.
Police confirmed two youths were detained in relation to damage and the matter would be referred to youth aid.