Children were seen running from the scene of a major blaze in Donald Rd, Kaitaia, that threatened homes.
Kaitaia's deputy chief fire officer, Craig Rogers, said that was one avenue being followed by investigators.
The blaze, on Wednesday afternoon, destroyed a couple of hectares of vegetation and threatened about 10 homes, flames reaching within two or three metres of at least two houses. More than 30 firefighters focused on protecting them as a strong nor-easterly wind drove the fire through gorse, tea tree and garden trees.
Volunteer crews from Kaitaia, Mangonui, Karikari and Rangiputa fought the blaze, two helicopters arriving about an hour after the alarm was raised and finally getting the situation under control. A crew from the Kerikeri Fire Brigade was dispatched to Kaitaia to provide cover for the town.
Mr Rogers said the Kaitaia brigade had been badly stretched with four calls received in little more than an hour. The first was to an injured child on Ninety Mile Beach, at 2.25pm, followed by the Donald Rd fire at 2.33, an injured child at Te Kohanga (Ahipara) at 2.42 and a road crash at Ngataki at 3.29.