A violent squall tore through the Auckland suburb of Devonport last night, lifting roofs , flattening trees and frightening residents.
The fierce windstorm lasted only a few minutes but left a trail of damage and briefly knocked out electricity.
No-one was hurt, although a driver had a lucky escape when a tree crashed through the rear window of her car.
The worst damage was around Wairoa Rd and Vauxhall Rd, where debris littered the road and sheets of corrugated iron hung from power lines.
Other parts of Auckland had thunder and heavy rain just before the strong winds, but escaped significant damage.
The city had been earlier warned to expect thunderstorms and tornadoes, but weather experts were reluctant to classify the Devonport event as a tornado.
WeatherWatch head forecaster Philip Duncan, said the weather system that passed through Auckland was unlikely to have had enough energy to cause a tornado.
"It needs a lot of hot air rushing up to do that and Auckland didn't have that.
"I am pretty sure it was just a straight line of wind, a gust of energy that punches out of the cloud."
He described it as a "localised squall of wind".
MetService said it would need to investigate the damage to officially determine if it was a tornado.
Duty forecaster Elke Louw said wind squalls of 110km/h were forecast for the region yesterday.
The Fire Service responded to many calls for assistance.
Power was being restored last night.
Michele Dodds was driving with her son, Taylor, 6, on Wairoa Rd when she felt small branches falling on the roof.
"Then suddenly it got extremely windy, then a trampoline was picked up and blown across the road. I had to slam on the brakes and it just missed us. It was all over within a couple of seconds ... It was a hazy, very violent shock of air."
At the North Shore Croquet Club on Wairoa Rd, sheds were uprooted and flung onto the pavement and large tree limbs were tossed on to the greens.
Committee member Ruth Castle, who lives on nearby Ascot Ave, wandered around the grounds in shock.
"It just came so suddenly and it's taken everything with it -sheds, trees, everything. There used to be a huge cedar just here ... I really can't believe it."
The fence of former Split Enz singer Tim Finn's $2.35 million Grahame St home was damaged.
Jacob Byron-McKay, 14, was playing football at a nearby park with a friend when he heard the roar of what he thought was an earthquake or a tsunami.
"We looked up and saw these branches being lifted up and then this big piece of iron started coming straight towards us so we just ran."
The garage door of Sarah Maher's Grahame St property was dented and buckled, and the glass of her back door was shattered.
The glass of her back door was also shattered by the tornado.
In Vauxhall Rd, part of an iron roof hung from a powerline and a wheelbarrow was wedged in a tree.
The roof was ripped from a house which also had several windows smashed.
Firefighters were last night working to cover the gaping hole left when the roof was torn off.