Fire safety officers will investigate a suspicious blaze at an unused timber mill at Kaitaia.
The fire service was called to the building, owned by the Kaitaia Timber company about 3.30am, northern fire communications shift manager Megan Ruru said.
Four fire trucks were called to the blaze, which was being treated as suspicious, and they were still at the scene, Ms Ruru said.
A fire investigator was on the way to the site to find out the cause of the blaze.
