No one has yet been killed by the bushfires raging across NSW, but a CSIRO expert warns that loss of life is likely.
While the extent of the devastation was unclear on Thursday night, one of the worst-hit areas was Springwood, in the Blue Mountains, where up to 30 homes were known to be lost.
Elsewhere, thousands of firefighters were struggling against around 100 blazes across the state - on the Central Coast and further north, the Southern Highlands and the south coast.
Some firefighters have suffered injuries, including one who's been taken to hospital with facial burns.
Despite the carnage, no deaths have been reported.
But Justin Leonard, CSIRO's research leader for bushfire urban design, believes it's likely people will die.
"History has shown us that on average one life is lost for every 17 houses," he said.
"The majority of these lives are lost within a few hundred metres of homes."
He advised people to use their home as a refuge and not to flee at the last moment."Monitor the home's condition while you shelter in case you need to exit the house on to burnt ground," he said.