That's how Dianna Bisset, who owns the Rocklily Road wildlife sanctuary with husband Warwick, described the scene as the Green Wattle Creek fire roared up on the back of 63km/h winds at 1am.

"It was pretty intense but we saved everything, including the house because we mowed, graded and raked all around," she said.

"We lived to see another day but it's been 360-degree firefighting for two days."

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The fire has been burning in national park northwest of Wombeyan Caves and in the Southern Highlands for weeks. By 6pm Tuesday it had destroyed close to 246,852 hectares and was at watch and act status.

The blaze flared up at about 3pm Sunday and crossed Langs Road. Thirty-one RFS trucks responded and worked overnight on containment lines. Operations director Lachlan Gilchrist said the flare-up took crews by surprise.

"It was very furious fire behaviour and was very challenging," he said on Monday.

Mrs Bisset believed six structures, including holiday huts in the area, had been destroyed on Monday night. It wasn't clear whether any were substantial houses and the RFS could not confirm numbers by the time of publication.

She knew of another neighbour who had lost a house and anticipated she would lose a shed.

Mrs Bisset described how the fire came over a hill above their home and then "raced back to the top."

"Everything was alight," she said.

"It was frenetic activity and crews had a hard time with the wind. They were trying to stop it taking out homes."

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Flames went over the top of structures, people moved caravans and the Bissets lost some trailers. If not for a containment line the RFS built a day before, Mrs Bisset said they would have lost their home.

They kept five wombats in the house, six in pens and released 26 kangaroos and wallabies. Outside, she could see "terrorised" roos "hunkered down" on a hill they had mowed and wombats and birds had reappeared on Tuesday.

The Bissets have hay inside the house and 25 bags of roo and wombat feed, as well as birdseed.

But she feared koalas and the critically endangered brushtailed rock wallabies had their areas burnt.

"Wombeyan Caves also has the largest number of Greater Gliders in the Blue Mountains National Park and the koalas are the most diverse in Australia," Mrs Bisset said.

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The sanctuary is located 24km northeast of Taralga.

The couple decided to stay and defend, given what they said were years of preparation. This included building their home to fire safety standard, extensive clearing and installing a sprinkler system.

"It wasn't good luck we saved everything; we were prepared," Mrs Bisset said.