It could take weeks to clean up damage in Kaitaia caused by sudden high winds and heavy rain, the Fire Service says.
At least 17 homes in the Pukepoto Road area were badly damaged on Saturday by what some residents have described as a tornado.
Roof tiles were ripped off and windows blown in when the storm hit the area shortly after midday on Saturday.
An eyewitness says the powerful winds and torrential rain lasted only about ten minutes.
Chief fire officer Colin Kitchen says roofs have been secured with tarpaulins, but the clean-up and repairs could take weeks.
Mr Kitchen says he expects the hard work will begin on Monday when insurance companies representatives and building inspectors will arrive to assess the damage.
Civil defence and victim support officers in Kaitaia have been helping residents whose homes were damaged. About 15 of the damaged homes are owned by Housing New Zealand.
A Housing New Zealand spokesperson says its contractors worked on site with emergency services on Saturday and will return on Monday.
Only one family chose not to stay in their home overnight due to broken windows, the spokesperson said.
Hospital lost part of roof
Deputy chief fire officer John Whitlow says the twister came from the direction of Ninety Mile Beach and cut a swathe through several streets and Kaitaia Hospital.
The roof was blown off the boiler room at the hospital, and trees fell over a transformer.
Nurse Katrina Tonks, who was working in the accident and emergency department, says she heard a deafening roar when high winds and rain suddenly hit the building.
Ms Tonks says it was a terrifying experience for staff and patients and describes the scene as like something from The Wizard of Oz with ceiling tiles being sucked up through the roof.
The hospital is operating normally despite the damage.
Anne Hallett, who works at Trees Company in Pukepoto Road says the storm was dramatic.
"Very high winds - the sky got very, very black. We started with torrentially heavy rain, which turned into fairly large pieces of hail - about the size of half a marble."
Ms Hallett says the noise made it difficult to work out what was happening, but it was all over very quickly.
There have been no reports of injuries.
MetService said on Saturday the weather system was moving south-east and heading for Great Barrier Island and Coromandel Peninsula.