Two more patients with minor injuries were assessed by St John upon arrival at Bridge Pa Aerodrome by rescue helicopter, and did not require hospital treatment.
A Helicopters Hawkes 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."
The Transport Accident Investigation Commission has sent three investigators to the crash site. They were expected to arrive at the site tomorrow morning.
The Commission has opened an inquiry into the helicopter crash that occurred at about 9am today at a remote location northeast of Waiouru.
The Chief Investigator of Accidents, Captain Tim Burfoot, says the accident involved a Hughes MD600N helicopter.
"The helicopter was on a commercial operation with 5 people on board when it crashed," Capt. Burfoot said.
The helicopter has been extensively damaged, he added.
The Commission opened an inquiry when it believes the circumstances of an accident or incident had - or was 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.
Rescue Coordination Centre NZ coordinated the response to the incident.
At 8.50am, RCCNZ received an alert from the ELT distress beacon on board, providing a location at Oturua Stream. The helicopter was undertaking a commercial survey operation in the area.
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.
"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."
One person was in a critical condition, two were in a serious condition and two others had suffered less serious injuries.
RCCNZ tasked two additional rescue helicopters with intensive care paramedics; one from the Hawkes Bay Helicopter Rescue Trust and the Palmerston North Rescue Helicopter. All patients have been taken to hospital.
"Our thoughts are with the injured passengers and we wish them a successful recovery," Wilson said.
The circumstances around the crash are still being established and TAIC are investigating.
- More to come
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