There were three suspicious fires involving schools in the Christchurch suburb of Wainoni overnight.
The Fire Service was called to a building on fire at Aranui High School on Breezes Road just before 1am on Saturday.
Then just after 2am, a rubbish skip at Avondale School 1km away was set alight.
Just before 4.30am, vegetation at the Kids First Kindergarten, also on Breezes Road, was set alight.
Shift manager Riwai Grace says all three fires were extinguished quickly, but there was some damage at Aranui High School, where a 30 x 10 metre building was well ablaze, on the western side of the building.
The building housed a community dental centre.
The second and third fires did not cause any damage to buildings.
Detective Sergeant Mark Reid says he is trying to get hold of CCTV footage in order to identify the arsonists.
Mr Reid says police know of two people who were near one of the lesser fires when it was lit.
He says the three events are being treated separately until officers have more information.
Loss to community
The dental centre was opened eight months ago by Canterbury District Health Board, which says it is an asset to the quake-stricken eastern suburbs.
It says the arson has added insult to injury.
One side of the building is badly burnt and air conditioning units are ruined.
DHB corporate services general manager Murray Dickson says the damage, which will cost tens of thousands of dollars to repair, should be covered by insurance.
He says he hopes to have the centre partially running again by Tuesday.