Early on Sunday 12 January, a series of homes around Lake Taupō were hit by arsons - including one with a family asleep inside.
Police are now seeking help from the public after the fires in Tauranga Taupō, Waitetoko and Hatepe. Two of the homes were completely destroyed.
While there were no injuries or loss of life, police are particularly concerned about the Hatepe blaze, where the family were asleep.
Detective Sergeant Andy Livingstone said they were aware the incidents were distressing.
"We would like to assure the public police are committed to fully investigating this matter and holding those responsible to account."
Police want to hear from anyone who saw vehicles travelling on and around State Highway 1 in the early hours of Sunday morning.
"In particular, police are interested in any vehicles entering or leaving the settlements of Hatepe, Waitetoko and Tauranga Taupō," Livingstone said.
"We would especially be keen to hear from anyone with dashcam footage that may have captured vehicle details.
"And of course, if anyone has any other information about these arsons or the people involved, we would strongly urge you to come forward and share that information with Police."