Three people are in Hawke's Bay Hospital after their helicopter crashed at Ngamatea Station, between Waiouru and the Kaweka Range, on the Napier-Taihape Road this morning.
As of 8.30pm, one male, in his 40s, remained in a critical condition in Hawke's Bay Hospital's Intensive Care Unit, while another male in his 40s was in a serious but stable condition.
One male, in his 30s was in a serious but stable condition, as of 8.30pm.
Two more patients with minor injuries were flown to Bridge Pa aerodrome by private contractors but were not transported to hospital as hospital treatment was not needed.
The Hughes MD600N helicopter was undertaking a commercial survey operation in the area, when at 8.50am, Rescue Coordination Centre NZ received an alert from the ELT distress beacon on board, providing a location at Oturua Stream.
RCCNZ Search and Rescue Mission Coordinator Dave Wilson said another helicopter from the same company was initially sent to provide a fast, initial response to determine the situation, with the Greenlea Rescue Helicopter from Taupo arriving on scene soon after to provide medical care.
Greenlea Rescue Helicopter pilot, Nat Every said they were the first helicopter on the scene by about 40 minutes.
They responded from Taupo with an intensive care paramedic on board, crewman and SAR personnel.
"Our intensive care paramedic was able to stabilise the seriously injured patients at the scene."
He said it became quite obvious that they were going to need additional resources and requested assistance from Hawke's Bay and Palmerston North.
RCCNZ tasked two additional rescue helicopters with intensive care paramedics; one from the Hawkes Bay Helicopter Rescue Trust and the Palmerston North Rescue Helicopter.
They used axes out of the helicopter to "cut a helipad closer to the scene" to allow easier access to the patients.
"Our paramedic remained on scene, as did we because he was the one that knew what was going on. He acted as the on-scene coordinator of the medical side of things and briefed all the incoming paramedics and steered the patients onto them."
"Distress beacons can summon life-saving help to people who need it and get them to hospital faster. In this particular case, the alert from the distress beacon was the only notification that the aircraft had crashed," Wilson said.
"Our thoughts are with the injured passengers and we wish them a successful recovery," Wilson said.
A Helicopters Hawke's Bay spokesman said the pilot has many years' experience flying helicopters.
"We have been in communication with the Civil Aviation Authority and Transport Accident Investigation Commission, both of whom will conduct a full investigation into the accident. We will be working closely with them and providing all the information required."
"At this stage it is inappropriate to comment or speculate on the cause of the accident."
He said their primary concern was the three injured patients and their families.
The circumstances around the crash are still being established. The Transport Accident Investigation Commission has sent three investigators to the crash site and they are due to arrive at the site this morning.
The Commission opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow the Commission to make findings or recommendations to improve transport safety.