Wildfires have destroyed dozens of homes in New Zealand, authorities announced Monday, saying it was a miracle no one was hurt when "a wall of orange" descended on a remote South Island village.

The blaze began in a mountain forest early Sunday morning and, fanned by strong winds, swept through the village of Lake Ohau, forcing residents to flee for their lives.

"The high winds meant the fire could not yet be contained and the situation may change rapidly with any shift in the wind," Fire and Emergency New Zealand said.

It said up to 50 structures were destroyed and conditions remained "challenging" on Monday, with 11 helicopters and nine fire crews attempting to contain the flames.

Waitaki District mayor Gary Kircher said the tiny Lake Ohau community had been devastated.

"Of the 60 or 70 houses, we believe that the majority have gone," he told Radio New Zealand.

"The reality is that it's a minor miracle no one has been harmed. If it had been anther 15-20 minutes it would have been a very different story."

Kircher described how residents awoke to find an inferno bearing down on them.

"I talked to a gentleman who got up to his dog (barking) in the early hours, opened his door and there was this wall of orange," he said.

"He was the one that set off the town fire alarm and helped to wake people... there's certainly some scary tales about how close it came to being an absolute disaster with fatalities."

Wildfires are relatively common on the South Island at this time of the year but the scale and intensity of the Ohau fire have been unusual.