Brave locals rescued three children from the wreckage of a helicopter crash before a farmer pulled the mangled aircraft out of the mouth of the Kekerengu River.
Two people were killed in the crash and three others - the children - were seriously injured before they were later airlifted separately to Wellington Hospital.
Two adults are reportedly feared dead with the children surviving the crash.
Investigators will comb through the wreckage tomorrow morning as they work to understand the circumstances that led to the crash.
The Transport Accident Investigation Commission has opened an inquiry and tonight appealed for witnesses – "especially anyone who may have captured the accident on their vehicle's dash-cam or other recording device - to please contact TAIC as soon as possible."
They have set up a perimeter around the wreckage prohibiting public access in order to protect evidence.
Fire and Emergency New Zealand (Fenz) operational insurance team member Darryl Papesch believed those rescued were children.
He was one of the first responders on the scene after visiting the local volunteer fire brigade and said locals had pulled everyone out of the wreck by the time he arrived.
"We were having conversations with them, not a proper conversation but they knew their names and how old they were," Papesch said.
"The three people injured were young ... they weren't adults, I'd say children, definitely children."
He said locals removed the five occupants before a local with a tractor pulled the helicopter up the beach and well-clear of the water.
"The locals were outstanding, in a chaotic situation they were outstanding.
"All three agencies, Fenz, police, St John, all worked together and just got on with it."
One of the locals, Ian Mehrtens, said he saw the helicopter fall out of the sky but didn't see it hit the ground.
"It did a few twirls, then it started to spiral and then it just dived," he told Newstalk ZB. "It landed on its side."
He quite often sees helicopters transporting tourists to land near The Store to grab a coffee or a meal, especially during the summer months.
"It was just another one coming in to land but it didn't land the right way," he said.
By the time he crossed the road and got to the wreckage, Mehrtens says other locals were trying to rescue its occupants.
"The poor old helicopter was on its side and pretty well smashed up, bits and pieces everywhere," he said.
"A couple of the passengers were crying out in pain … there were a couple of guys there trying to lift out the three children that were in it.
"We managed to get them out but it took a while because we were concerned about it blowing up."
The locals managed to get the people out, who are believed to be children, with Mehrtens carrying a little girl to safety.
Mehrtens said she looked to be okay but was concerned about the welfare of her mother.
Afterwards, the locals made sure everyone was safe and sound and out of the tide.
The tractor owner told TVNZ: "We all just heard a bang as it hit the ground and all the locals rushed out and rallied around with blankets and that sort of thing, and we managed to get some of the people out of the helicopter."
He grabbed his tractor and pulled the helicopter away from the water's edge "out of harms way".
He said locals "without a doubt" managed to save lives with their quick actions.
"There was a lot of us who did what we could. The local nurse heard about it and came rushing down. I call it a team effort."
The crash took place outside The Store, a popular spot for heli-tourists to visit, in the small town located around 30-kilometres north of Kaikōura, at 12.42pm.
The helicopter was an Airbus Helicopter EC120 and is came from Christchurch.
Mehrtens wife, Coastal Lodge owner Lyn Mehrtens also watched as the chopper plunged to the ground, spinning in circles as it descended.
"We just watched it go round and round and round," said Mehrtens.
"It's scary. You're just so helpless. You can't do anything."
Papesch believed the helicopter was partially in the surf of the Pacific Ocean coast.
Harald Hendel, TAIC's chief investigator of accidents, says there may be people who saw what happened, given the location of the accident adjacent to a busy café on State Highway 1.
He has appointed an investigation team and they are scheduled to be on site tomorrow morning.
"The Investigation team have expert knowledge of helicopter operations, engineering and maintenance.
"Their initial work will include inspecting the wreckage, mapping the site, and talking with witnesses. Further evidence gathering in coming weeks and months will likely include examining the helicopter's components, seeking any recorded data from the helicopter's electronics, and obtaining maintenance records."
Rescue helicopters were sent from Christchurch, Nelson Marlborough, and Wellington, and a commercial helicopter was sent from Kaikōura.
Each of the rescue helicopters then flew a patient each to Wellington Hospital, said Simon Duncan, general manager of GCH Aviation which operates rescue helicopters and air ambulance services.
A spokesperson for the Capital and Coast District Health Board said the three patients were being assessed in the emergency department.
"All three rescue helicopters from around the region were sent to the scene not knowing what they are going to come across," he said.
Each helicopter has one pilot and two paramedics on-board.
"It's a very sad time of year for that type of thing to have to go through," Duncan said.
Kaikoura mayor Craig Mackle said his thoughts were with the friends and family of those on board the flight.
"It's sent shockwaves through the community.
"It's definitely making everybody think about their families and Christmas and everything."
Mackle didn't have any information about who was on board the flight or who died.