The forest fire still burning in places north of Napier started around one of several logging skid sites in the area, according to a long-serving Hawke's Bay firefighter.
Bay View Volunteer Fire Brigade chief Richard Hinks confirmed the likely site but said on Wednesday the actual cause had not been determined.
"It has been pretty full on," said Hinks, who has been fighting fires in the Bay View, Tangoio and Eskdale area for more than 30 years.
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"It is the biggest fire I have seen. It started at a skid site but the cause has not been determined yet."
A skid site is a designated area where harvested logs are processed before being loaded on to trucks for removal.
Firefighters continued extinguishing the remains of the fire which spread across at least 300 hectares since Monday.
Safely contained within the area bounded by to the east by Tangoio Settlement Rd, despite it coming within metres of crossing the gravelled road on Monday night, the fire was today under control. Helicopters were still available but no longer involved in the fight, said incident controller Trevor Mitchell.
But the higher-ridged section of Tangoio Settlement Rd between the Waipatiki Rd junction and State Highway 2 at the Devil's Elbow remained closed to traffic, although evacuated homeowner Peter Boyce had been allowed to return to the property.
Long time SH2 Tangoio resident Ross Cook told Hawke's Bay Today the fire spread quickly after it was first noticed, and as the "bush telegraph" became increasingly concerned he realised: "It's not just for a small hangi."
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"One of my friends works at Mobil down the road and gave a neighbour a call about seeing smoke," he said. "I said Nah, that's from the Australian bush fires."
A closer look confirmed the suspicions and he said: "She was a fire for sure. Then I saw a helicopter with a monsoon bucket."
At night the fire created a "massive orange globe", he said.
The property of sister and Tangoio Settlement Rd resident Sue Hill had become a base for the firefight, her husband mowing the lawns to help create a helicopter landing pad.
"I don't think we have ever had a fire this big," she said, telling how she started packing her bags as the fear of the spread of the fire increased.
Horses were moved to Bay View to alleviate one of the possible problems, Cook saying: "Horses and helicopters don't mix."
Between 50 and 70 firefighters continued working today, mainly on the perimeter.
Mitchell said people should stay away from the area to enable the personnel to complete the job.
Temperatures up to 23 degrees are expected on Thursday, but are expected to be back close to 30deg by Sunday, with the hottest parts of the summer still expected around the end of the month.
Fire and Emergency and Pan Pac forestry crews have reported good progress on securing the 12km perimeter of the fire, a FENZ statement said tonight.
Some areas of deep-seated burning remained in the centre of the fire ground and crews would be progressively working to extinguish them over the next few days, and smoke would be seen from some parts of the site.