Northland's rural fire chief Miles Taylor says investigators are following strong leads on how and where Wednesday's Karikari Peninsula fire started.
Mr Taylor told Radio New Zealand's Checkpoint he had been informed that the point of ignition had been identified and the area has been sealed off.
He says investigators will now carry out a full scene examination and then begin talking to witnesses.
The fire swept through scrub and destroyed several buildings on Wednesday evening, causing people to flee for their lives. Several leapt into the sea to escape the flames, which destroyed at least three homes and a caravan.
Salt Air pilot John de Ridder and Department of Conservation ranger William Macrae died when their helicopter crashed into the sea off the Peninsula as they were helping combat the fire.
Police suspect the fire was deliberately lit and have announced they will review all recent rural fires in the Far North.
Wednesday night's blaze was the 14th suspicious fire on the remote peninsula in the past two years. There was another fire in the same spot just two weeks ago.
Northland police commander Russel Le Prou says anyone with information about the fire and who wants to remain anonymous should call crimestoppers on 0800 555 111.
Extra DoC rangers and firefighters from outside Northland have been called in to relieve local teams and are how dampening down the remains of the fire, which scorched 100 hectares of Karikari Peninsula.
Call for manslaughter charges
The head of the company that employed the helicopter pilot says manslaughter charges should be laid against anyone arrested.
Salt Air's chief executive Grant Harnish says Mr de Ridder, known as Prickles, was an extremely experienced pilot who was well known throughout Northland and the New Zealand aviation community.
He called his death a criminal waste and said it was indicative of his nature that his final act was a selfless attempt to rescue people whose lives were in danger.
He told Checkpoint the deaths were not an accident, and he would be beside himself if manslaughter charges were not laid.
There's no doubt its manslaughter. What would be the difference between setting a building on fire with peole inside it or setting a bush on fire in 20 to 30 knot winds with houses downwind of that and then people like Prickles and Willie go in to help other people out and lose their lives doing it.
Earlier, Far North mayor Wayne Brown said it should not have taken the death of two people to draw attention to the problem of fires being intentionally lit in the region.
He says he's been warning central government and police for some time that something needs to be done to stop arsons throughout Northland.
It shouldn't take tragic deaths of very good people to get these things discussed, he says.
The council has welcomed the police review of past cases, saying it would be welcomed by the worries community as long as it was a serious review and not a fob-off.
CAA investigating crash
The Civil Aviation Authority (CAA) on Friday began its investigation into the helicopter crash.
Investigators were in Paihia on Friday to speak to Salt Air.
A CAA spokesperson says planning is also underway on how to retrieve the craft, which is under seven metres of water.
A barge that will be used as part of the recovery operation is heading from Paihia to Karikari and is due there on Saturday.
A dive team is also heading to the area from Paihia.
The CAA is also consulting maritime authorities about how a forecast swell might affect the recovery operation.