A man died in a helicopter crash while fighting the Christchurch Port Hills fires.

Police confirmed a helicopter went down in the area above the Sugarloaf car park just after 2.30pm on Tuesday.

Superintendent Lane Todd confirmed the pilot, a man, had died.

ALDEN WILLIAMS/FAIRFAX NZ The fatal helicopter crash on the Lyttelton side of the Port Hills.

"I can confirm there was only one occupant and unfortunately he has died at the scene."

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Todd said it was "too early to determine exact specifics of the crash".

GEORGE HEARD/FAIRFAX NZ A wider angle of the crash site, at the bottom of the frame.

Investigations by police and the Civil Aviation Authority had been ongoing and would resume on Wednesday morning.

Cordons will remain in place on Summit Road ant the intersection with Dyers Pass Road overnight.

A St John spokesman said they "extend our condolences to the colleagues of the deceased".

Principal Rural Fire Officer Douglas Marshall says the incident was a tragedy.

"Those involved in fighting fire on the ground and in the air make a huge contribution to keeping our community safe, often at considerable risk."

New Zealand Helicopter Association chairman Pete Turnbull said flying in those conditions was a "very busy environment".

"There is a lot going on around you. There's obviously a sense of urgency … with buildings and the possibility of people's lives at stake."

He said companies were audited and certified before they could be called to fight fires, and pilots had to have knowledge of wildfire behaviour, flying in low-visibility and mountains, and flying with loads before they could take part in these operations.

"These are people that know what they're doing and know how to operate their machines."

Operations were planned and controlled so aircraft were following a track which did not cross each other's path and were generally safe, Turnbull said.

"The systems designed also to remove as much of the pressure from pilots as possible and make everything flow smoothly for them, allowing them to concentrate on the job and not the outside factors."

"The helicopter industry is relatively small in New Zealand and we all feel for the pilot that died in the course of his duty."

Christchurch mayor Lianne Dalziel released a statement on the Christchurch City Council Facebook page saying her heart goes out to the family.

"There really is no greater sacrifice than to risk your life in the service of others.

"I know I speak for the whole Council when I express sincere gratitude to everyone, who is doing their best to get these fires under control. Our thoughts are with you all."

Police and the Civil Aviation Authority would investigate the circumstances surrounding the crash.

A Civil Aviation Authority spokesman said all air flight operations in the firefighting zone had been suspended to protect other pilots. The restriction applied had been extended to 9pm, in relation to all air traffic in the area, except firefighters.

A Christchurch Helicopters staff member said none of their helicopters were involved.

Up to 15 helicopters had been fighting the two out-of-control scrub fires, and it was understood all had been grounded following the crash.

The fires – the first in Lansdowne on Early Valley Rd, and a second that started in a car park near Marleys Hill, off Summit Rd – took hold on Monday.

They have spread over 600 hectares, and it was expected firefighters would be needed for another two or three days.