Three people reported killed
Damage reported across west Auckland and North Shore
Tornado reported on Auckland motorway
Roads closed include SH 18, Wallingford Way in Hobsonville, Waimarie Rd in Whenuapai and Moselle Ave in Henderson.
150 homes deemed uninhabitable
Public transport services affected
Auckland Airport withdraw staff from tarmac
Electricity was off in numerous parts of Auckland including Henderson, Greenhithe, Hobsonville, Riverhead, Meadowbank and St Johns.
There was widespread surface flooding on roads and motorways throughout Auckland and motorists are urged to take care or stay off the roads if possible.
Andy Gummer of St John said at least seven people had been transported to Auckland and North Shore hospitals.
"There might be some critical,'' he said.
A tornado hit Hobsonville during the storm, tearing down trees and ripping panels from the motorway.
Fire, police and ambulance raced to multiple callouts in Hobsonville and Upper Harbour.
Defence Force personnel were going door to door to check on people and emergency services were trying to clear blocked roads.
At 1.52pm MetService weather radar detected thunderstorms near Auckland, Orewa, Albany, the inner Hauraki Gulf, Daily Flat, Whangaparaoa and Silverdale.
Police Superintendent Bill Searle said a series of tornadoes passed through Hobsonville, and one of those touched down on a subdivision, causing damage to trees and buildings.
He told a media conference at Whenuapai Air Base that about 12 uniformed USAR personnel, who happened to be in the area at the time were gathering intelligence to help police but had not been formally deployed.
The Defence Force was on standby, and an emergency centre has been set up at the air base.
Mr Searle said the forecast was for more bad weather and people in the Hobsonville and Greenhithe areas should stay inside.
The Fire Service had received between 80 and 100 calls and more than 12 appliances have been sent to the area.
A Fire Service spokesman said there appeared to be "significant building damage'' and a number of people had been trapped.
Fire Service spokesman Scott Osmond said a roof had caved in at a Mastertrade store and there were reports of chimneys being toppled and roofs blown off buildings in Hobsonville.
Fire Service area manager Murray Binning said appliances were responding to damage more widespread than the 1km zone at a construction site.
"There are houses with roofs off scattered all over west Auckland, so we're dealing with those too,'' he said.
Whenuapai resident Suzanne McFadden said the tornado was like a roaring "juggernaut''.
"We have no power, it honestly looks like a bomb has gone off in the street.
"I saw it coming across the river, the air went very electric and the sky went black. And then the wind started to whistle.''
She said she saw trees coming up the street and then ran to the hallway inside for cover.
"We were in the middle of it. It was a roar. ''
She said century-old pine trees had been uprooted, one even crashing through her neighbour's garage - crushing a van inside.
Because road access was blocked, residents were concerned for the wellbeing of their children at nearby Whenuapai School.
"We can't get out and nobody can get in, there are live power lines on the road. People who are getting home now are walking miles just to get home.
"This was like a juggernaut roaring through here. Everyone is really shaken up.''
Witness Matt Eade said he was in his lounge when the tornado hit.
"The wind picked up real fast and then it rained real hard. The hardest wind you can imagine was swirling around; it would go one way real fast and then back the other way - it kept changing directions. We were standing away from the windows because we were expecting them to crash in. I thought it was one of those situations where we thought we could get swept away.
Power was off at his house and firefighters had asked if he wanted to evacuate.
Local resident Jordan Carter said high winds had hit his house in Whenuapai.
The fence had been blown down, trees uprooted and the lid of the spa pool gone, he said.
Prime Minister John Key extended his condolences to the friends and families of those who had died.
"This must have been an extremely frightening situation for many people in the local community,'' he said.
"This extreme weather event occurred in the heart of my electorate as well as Paula Bennett's electorate. I have been kept informed of the situation throughout the afternoon and am continuing to receive updates.''
Auckland Mayor Len Brown and councillors were briefed by the council's civil defence head and Mr Brown was to go to the operational base at Whenuapai this afternoon.
