The fire has destroyed at least two homes and forced at least five residents to flee their homes.
The experienced Northland pilot and the Far North DoC worker died when their Squirrel ZK-IMB helicopter plunged into the sea, about 350m off the coast.
Mr de Ridder is thought to live in KeriKeri and One News reported he was a member of the local volunteer fire service.
Minister of Conservation Kate Wilkinson said she was "deeply saddened" by the tragic death of Mr MacRae.
"My thoughts and condolences are with his partner, family and colleagues in the Kaitaia office and Northland conservancy.
"William died trying to help others. He was an experienced, well-known and well-liked DOC staffer and he will be greatly missed in the community.
"I also wish to offer my deepest condolences to the family of the pilot who died in the crash."
Rescue Coordination Centre search and rescue officer Conrad Reynecke said the search would now be stood down, with police taking over responsibility for body recovery, formal identification and informing next of kin.
"While the search has come to an end, we are saddened that it has ended in this way. Our deepest sympathies are now with the families of the two men."
The Civil Aviation Authority is now investigating the crash.
Divers used to identity missing men
Mr Maxwell said an oil slick has been found not far from the fire.
"We're 99% sure the helicopter is there, we don't know any more than that and what we're doing at the moment is obviously supporting family and supporting our staff.''
Whanagarei police communications manager Sarah Kennett says a police dive squad is on the way from Wellington to recover the chopper and its two occupants.
She says police search and rescue teams are at the scene of the helicopter crash and have been out in a boat.
Maritime New Zealand spokesman James Sygrove says the chopper is thought to be 7m underwater.
"It's underwater, about 300 metres off the coast of the peninsula of Moana Bay as I understand it.''
Mr Sygrove says the wreckage was discovered by the crew of a fishing boat which had spotted an oil slick on the water.
A diver was put down but was unable to get inside the machine.
He says the next step is to try to identify the situation on board.
Last night two helicopters, from Whangarei and Auckland, were called to the area last night but only one could take part in the search because the other was not equipped with night vision equipment.
Both helicopters took part in the search from daylight today.
A land search and rescue coordination team arrived about 2am and conducted operations on the ground with assistance from police.
Police northern communications spokesman Inspector Matt Rogers said the EPIRB beacon, which raises an alarm if the helicopter crashes, had not been activated.
Spate of Northern fires
While the cause of the fire has not yet be ascertained, it is one of many in Northland in recent weeks.
Only a fortnight ago, another fire tore through the Karikari Peninsula, taking firefighters three days to extinguish.
Between 2.20am and 3.30am on November 26, Kaipara and Dargaville's fire crews were called to suspicious fires in Parore, Kaihu and two in Mamaranui.
Later that day two appliances from Paihia were called to tackle a small scrub fire in Opua, near a chemical storage facility.
More than 100 firefighters were called to a blaze in White Cliffs forest, near Horeke, on November 23. The fire, which spread through 318ha of forest, was believed to have started when a planned burn-off got out of control.
Margaret Mutu: Locals say fire is deliberate
Meanwhile Auckland academic Margaret Mutu is on her way up to Karikari Peninsula where she and several family members own homes.
She says the small community is devastated over the missing men onboard the helicopter and their kaumatua is out on the sea now performing a karakia and a rahui has been placed banning all fishing and water activities.
Professor Mutu says locals are convinced the fire raging on the peninsula is deliberate as they enforce such strict fire controls in the area.
'Pretty bloody scary'
Meanwhile Far North District Council chief executive David Edmunds today told Radio New Zealand authorities were reasonably confident the fire was now under control.
"It is blowing out towards the sea, so at the point it obviously cuts off. We're reasonably happy on the fire front as far as engaging our staff and getting out there dampening it down."
A welfare centre has been set up at the Karikari Fire Station for evacuees and police are investigating the cause of the fire.
Last night five people escaped the flames by fleeing into the water and were rescued by the Coastguard.
A sixth person was feared missing after the fire broke out about 7pm. That person was located later.
The fire has already destroyed at least two homes.
Ground crews are trying to contain it, but the Fire Service says there's the potential for it to spread into an area containing more houses.
People who think they may be in any danger are being urged to leave as soon as possible.
A Matai Bay Rd resident, who asked not to be named, lives 2km from the blaze and drove over to see it with his own eyes.
"My mate's house has burnt down. The fire was massive and it was so windy and scary, fanning the flames. The entire cape is burnt down. It's pretty bloody scary, windy as, blowing it all over the show. The fire is still going, it's crazy."
By midnight, more than 40 hectares of trees and scrub at the end of the Karikari Peninsula was alight but firefighters were unable to extinguish it because it had become "too dark and dangerous" with a strong easterly wind fanning the blaze, said Fire Service spokesman Scott Osmond.
The total number of people evacuated from their homes was unknown last night, but at least five people fled into the sea in fear of being engulfed by flames on land.
"They are all safe and unhurt," Mr Osmond said.
Earlier, there were fears one person was missing, but they were soon found.
Evacuees were taken to the Karikari Community Hall, which was being used as a welfare point.
John Beachman, of the Northern Rural Fire Authority, said late last night that the fire "had done its run" and stopped at the coastline, so firefighters were able to concentrate on the edges.
"It's travelled a couple of hundred metres. It's quite intense. The spread of the fire has massively diminished because it's not running."
He said firefighters would continue to use monsoon buckets to douse the blaze, which would burn through the night.
Second fire in a fortnight
Mr Beachman said the fire started near Matai Bay Rd, but it was too early to say whether it was suspicious.
"We always investigate these things. The ignition point has been identified by police, so that will be looked at closely by investigators."
Two weeks ago, firefighters battled for more than three days to contain another major scrub fire on the Karikari Peninsula.
The fire was thought to be suspicious. At the time, Principal Rural Fire Officer Miles Taylor said it was part of a worrying trend in the area.
The earlier blaze threatened campers and baches at Karikari Beach and Maitai Bay.
Flames quickly spread through coastal scrubland, reaching the road and then jumping across into a paddock above Maitai Bay. Mr Taylor said at the time that arson and nuisance fires were taking a mounting toll on Far North communities.
His greatest concern was that sooner or later a wildfire might result in serious harm or death.
"We've been really lucky so far, but I think it's only a matter of time," he said.
"Wildfires can quickly spread into places where people are living, or recreating.
"I'm really worried about what will happen if we don't get on top of this issue."
In Karikari, a fire permit is required at all times, unless a total fire ban is in place.
Helicopter crashes while surveying scrub fire
View Northland fire and helicopter crash in a larger map
