Two fires at the same property within a few days are being treated as suspicious.
Ruakaka firefighters were called to a house fire in Princes Rd, Ruakaka, on Monday night - and were called back to the same property on Thursday at 8.21pm, after residents found a caravan on fire.
Ruakaka Fire Station Officer Jeff D'Ath said both fires were discovered early so there was only minor damage.
Whangarei police spokeswoman Sarah Kennett said the culprits burned a rear panel on the caravan and on Monday night a small fire was lit on a foundation pile on the side of the house.
"Both fires were relatively small but are of concern considering the proximity to the home owner," she said.
Mrs Kennett said on Monday night police dogs were used to try to track whoever was responsible, but no one was found.
The resident of the house managed to put the Monday night fire out with a garden hose and the caravan fire was put out by firefighters "fairly quickly".
A fire investigator was on scene yesterday. Anyone with information should call police on (09) 430 4500 or Crimestoppers on 0800 555 111.