Supplies may be flown into Auckland's isolated west coast communities

Auckland Emergency Management may fly supplies in to areas of the region's west coast with no power or road access.

Around 300 homes in Muriwai are in peril from slips, while 20 homes were evacuated in Piha yesterday and five homes in Karekare have been destroyed in slips.

Karekare resident and former Waitākere City mayor Sir Bob Harvey said they are completely cut off, with 10 visible major slips.

They have been walking in food supplies, Sir Bob said.

"We've got a system going where we can drive down to the slips and cart them round the edges. It's a bit of a mule trip over a hump and bump through the bush and we can take cartons of food down."

It was an emotional time for residents who are dealing with the trauma of losing houses and the danger of slips, he said.

"Five [houses] have come down including a terrific house up on the hill built by a beautiful loving couple and they were in it when it started to move. I guess of all the houses we thought wouldn't move, this one did. They are now safe."

Sir Bob said another house resembled "matchwood" after collapsing in a slip - its occupants, a woman and her two children, now safe.

The Surf Lifesaving club has become a lifeline, he said.

"The whole of the Karekare community is truly cut off, no one can get down and no one can get up so the Surf Club has become a vital communication and comfort stop."

It has a power generator and 30 bunk beds, all full.

"We have adequate accommodation. I didn't realise it would be so emotional, we're kind of traumatised in a way. We're going to suffer from post Gabrielle trauma it's going to affect us for a long time."

Auckland Council director of regulatory services Craig Hobbs said they still did not yet know the full extent of damage in the coastal communities.

National state of emergency: What you need to know

• The New Zealand government has declared a National State of Emergency, to assist in the response to Cyclone Gabrielle.
• The declaration will apply to the six regions that have already declared a local State of Emergency: Northland, Auckland, Tairāwhiti, Bay of Plenty, Waikato, and Hawke's Bay.
• A national state of emergency gives the national controller legal authority to apply further resources across the country and set priorities in support of a national level response.

National Emergency Management Agency advice:

• Put safety first. Don't take any chances. Act quickly if you see rising water. Floods and flash floods can happen quickly. If you see rising water do not wait for official warnings. Head for higher ground and stay away from floodwater.
• Stay at home if it is safe to do so. But have an evacuation plan in case your home becomes unsafe to stay in.
• If you have evacuated, please stay where you are until you are given the all-clear to go home.
• People should stay up to date with the forecasts from MetService and continue to follow the advice of Civil Defence and emergency services.
• Do not try to walk, play, swim, or drive in floodwater: even water just 15 centimetres deep can sweep you off your feet, and half a metre of water will carry away most vehicles. Flood water is often contaminated and can make you sick.