Do you have any information on this morning's crash?

Three people are confirmed dead after an Air Force Iroquois helicopter crashed north of Wellington this morning, says the Defence Minister.

Dr Wayne Mapp earlier said four people had died in the crash but a spokesman for the minister confirmed to that Dr Mapp had been given the wrong information.

Air Force spokesman Kavae Tamariki said the fourth person is alive but in a serious condition in hospital.

The helicopter, part of No. 3 Squadron, was travelling from the RNZAF's base at Ohakea and was due to take part in a fly-past of the Wellington Cenotaph while in formation with two others during this morning's Anzac commemorations.

It came down at Pukerua Bay, near the Paekakariki Hill Road.

Wellington Westpac Rescue Helicopter operations manager Dave Greenberg said a paramedic was winched into the helicopter crash site.

"At that point we didn't know if anyone was alive," Mr Greenberg said.

He said an injured man was found and winched into the rescue helicopter before being taken to a nearby ambulance and transported to Wellington Hospital.

Mr Greenberg said the paramedic was then able to confirm the three others were dead.

"The helicopter is upside down. I would say it went in pretty hard," he said.

Acting Chief of Defence Force Rear Admiral Jack Steer said he could confirm the deaths "with deep regret".

"Next of kin have been informed or are in the process of being informed of the tragic deaths of these young people in the service of the NZ Defence Force," he said.

Dr Mapp, who is at the Anzac commemorations in Auckland is describing the accident as a "brutal blow".

Two Iroquois helicopters are in the air, circling the crash site.

Central police communications shift commander Stephen Ross said four people were on board at the time of the crash.

He could not say if all were Air Force personnel.

Mr Ross said police got the call at 6.45am but he was not sure what time the crash happened.

Pukerua Bay resident Kathy McLauchlan told NZPA she could see the crash site from her window.

Weather conditions at the time of the crash were "extremely misty", she said.

"Since the mist has lifted, we can see it."

The crash happened quite high on the hills overlooking Pukerua Bay, Ms McLauchlan said.

Defence Force communications director Commander Phil Bradshaw said there would be no official comment until the force had established what happened. A media conference has been scheduled later this afternoon.