Emergency Management Minister Kieran McAnulty says he would not be surprised if the death toll in Hawke's Bay rises in the aftermath of ex-tropical cyclone Gabrielle.

Two people have already died in the area - a woman died in Putorino overnight, in northern Hawke's Bay, when a bank collapsed onto her home, and a person found was found dead on the shore in Bay View, Napier on Tuesday.

The severe weather this week prompted a national state of emergency declaration on Tuesday morning, covering Auckland, Northland, Tairāwhiti, Bay of Plenty Region, Ōpōtiki, Whakatāne district, Waikato Region, Thames-Coromandel, Hauraki district, Waikato district, Tararua District, Napier City and Hastings District.

As of Wednesday, 9000 were displaced just in Hawke's Bay, by Cyclone Gabrielle. Overall across the country, the number is about 10,500.

McAnulty says the cyclone had moved off the coast of New Zealand and accordingly the worst of the storm was over, but "we're not out of danger yet".

"Sadly we've lost two lives - both in the Hawke's Bay - this is incredibly upsetting for everyone involved and my thoughts are with the family and friends as they face this tragic loss."

Emergency services are still carrying out rescues and land searches in several places.

McAnulty says the roading network in Coromandel had been decimated. In Tairāwhiti, he says it was a relief most of the power had been restored and the Gisborne mayor was confident, with the airport now cleared, Defence Force planes could get in with supplies - but was worried about conserving water.

"That doesn't even touch on Northland with the huge power cuts up there, and the effect that it's in particular having on the rural communities."

Local councils would be surveying local roads and assessing whether they were safe to pass or not, he says.

"If it's just floodwater they will still assess whether a road is safe to pass. Just because a landslip has been cleared it doesn't mean it's safe."

Waka Kotahi are responsible for state highways and "are on to that", he says.

Hawke's Bay and Wairoa

More than 300 people rescued in Hawke's Bay on Tuesday are now being cared for in Civil Defence centres. It included a rescue of about 60 people from the roof of one large building, McAnulty says.

"The rescue coordination centre have 25 remaining tasks of individual or family groups that require rescuing and they are working through. These are being triaged and there are 12 helicopters undertaking the rescues.

"Emergency services are confident they will complete this task today, and there are no further calls coming through regarding rescues in Hawke's Bay."

Evacuations were under way in Hawke's Bay, with 9000 people estimated to be displaced, he says.

some 3000 are in Civil Defence centres.

Power remained out across the city of Napier on Wednesday morning. Wairoa's river had burst its banks overnight, and the town was cut off by road with only one day worth of food and two days of drinking water.

"Wairoa remains cut off, but NEMA has been able to communicate with the local CDEM group via satellite phone and NEMA personnel are en route to provide a needs assessment report at which point we will meet the need required," McAnulty says.

There had been a clear link of communication between NEMA and the local Civil Defence in Wairoa, he says.

"Power is back on in Wairoa to a large degree. There are two evacuation centres - the war memorial hall and the presbyterian hall - Wairoa college is there as a backup as well.

"FENZ have regular communication so we're in a much better position than we were yesterday - uncertainty causes anxiety and concern but we still don't have a full grasp of the situation there because we want to have people on the ground and that's happening as we speak."

The main focus on Wednesday was understanding the needs of the communities across the country, he says, and they were utilising all options.

"I was down in the bunker earlier, there are people working on solutions to that to get those basic provisions to those isolated towns."

Communication difficulties

McAnulty had spoken to the mayors of Gisborne, Hastings, central Hawke's Bay, and Tararua. He has been unable to speak to the Napier and Wairoa mayors but has heard indirectly through Civil Defence.

"Spark and Vodafone are choppering connection supplies to Gisborne today so I'm hopeful we'll be able to re-establish connection as soon as possible.

"My key message to everyone remains the same. Safety first. Look after yourselves and your families.

"This is a significant disaster and it is going to take many weeks for those areas most affected to recover."

He advised people to keep track of official communications and follow official advice.

Where people did not have power or communications, he says people should rest assured the people on the ground have a good grasp of what is needed in the local communities.

"There are certainly isolated communities but that's not unusual in a response."

How the country responded to a disaster was vital, but the recovery was just as important, he says.

"We are in this for the long haul."

Defence Minister Andrew Little says in terms of the defence force contribution to the response, there were more than 250 personnel across the Navy, Army and Air Force.

"Four NH90 helicopters - one in Northland and three in Hawke's Bay have been utilised and a fifth will be available for deployment in the next day or two.

"One Seasprite helicopter is in action and today has been tasked with a surveillance flight across Coromandel and the Bay of Plenty."

There were also trucks, unimogs and other vehicles in use, with an additional convoy of trucks and more than 100 personnel leaving Linton base today.

Little says many more Defence Force members were on short stand-by for deployment from bases across the country and would be ready to relieve those currently in service.

Prime Minister Chris Hipkins has described Gabrielle as the most significant weather event in New Zealand since Bola in 1988.

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.

- RNZ.