The tornado that ripped through Auckland today sounded like a "747 was flying right overhead", a witness says.
One man was killed in the tornado which struck first in Albany about 3pm.
More than a dozen people suffered injuries, some of which were critical, as the twister left a trail of destruction in Auckland suburbs.
One eyewitness said the tornado came within 200 metres of a school.
The Fire Service said 74 calls for help were made, while the police responded by sending at least 15 units to the North Shore.
About a dozen cars were overturned by the tornado with people trapped inside, Inspector Gary Davey, Acting Commander for the Waitemata Police District, said.
Davey was unable to confirm the age of the man earlier tonight.
Eyewitness Simon Lambert said the tornado sounded like a "747 was flying right over head".
"It was that noisy and that's what really got to us the most," he told ONE News. "It was just incredible."
Prime Minister John Key said he had left a message of support for Auckland Mayor Len Brown "offering any support the government may be able to offer the people of Auckland".
Aside from the damage to residential and commercial properties, power was cut in Glenfield after a power station was damaged.
Shortly after the tornado struck, Lucy Zee posted on Twitter: "Albany mall has been evacuted. Im shaking so bad. Roof collapsed. I thought I was gonna die".
Johndhanna said a number of buildings had been "trashed" and there were iron sheets in the air.
The tornado "came from nowhere", Alex Vaz said.
"We all turned around and then this massive tornado just broke out," he said.
"We saw it go right through Pak'NSave and we saw like big cars, little cars flying everywhere and then they came through here and we just saw the whole roof of the building fly up into the air."
Other witnesses spoke of "bits of roofing being ripped up".
Eyewitness Celena Sinclair told ONE News the tornado came within 200 metres of where parents were collecting their children from Pinehill School in Albany.
"It was mesmerising but terrifying - a huge grey black funnel and the roar was deafening," she said.
"The school did very well to advise everyone to get inside while we watched it travel north west away from us. The amount of debris and iron high in the air was incredible.
Police had planned to close the Auckland Harbour Bridge but that plan was dropped as the twister veered away from the bridge.
The worst tornado in New Zealand struck Hamilton in 1948, killing three people and destroying dozens of homes. In August 2004 a tornado destroyed a house in Taranaki, killing its two occupants.
North Shore Events Centre has been set up as an evacuation centre for people affected by the Auckland tornado.
Civil Defence said Work and Income, Victim Support and the Salvation Army will be on hand to help people. People needing help should call 0800 463 010.
Emergency services are still going through the damaged buildings in the Albany Mega Centre to ensure no one else is trapped inside.
One house in Roseberry Ave, Birkenhead has been declared uninhabitable and arborists have been working to clear trees that have fallen over.
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