Australian Prime Minister Scott Morrison has called up about 3,000 reservists as the threat of wildfires escalated Saturday in at least three states. He said 23 deaths have been confirmed so far this summer, including two on Saturday, and "we are facing another extremely difficult next 24 hours."

"In recent times, particularly over the course of the balance of this week, we have seen this disaster escalate to an entirely new level," said Morrison.

The early and devastating start to Australia's summer wildfires has already burned about 5 million hectares — 12.35 million acres and destroyed more than 1,400 homes. Two people died on Saturday as Australia braced for one of the worst days in the crisis, with strong winds and high temperatures forecast to bring flames to more populated areas, including the suburbs of Sydney.

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Temperatures in parts of the Australian state of New South Wales are expected to soar in the mid-40s Celsius — about 113 Fahrenheit.

New South Wales Premier Gladys Berejiklian called on people in threatened areas to leave while they can.

"All of the major road networks are still open but we can't guarantee that beyond the next few hours. So there are still windows for people to get out," Berejiklian told reporters.

Residents look on as flames burn through bush on January 04, 2020 in Lake Tabourie, Australia. BRETT HEMMINGS/Getty

The fire broke containment lines Friday and was described as "virtually unstoppable" as it destroyed buildings and burned through more than 14,000 hectares - 35,000 acres - of Flinders Chase National Park. While the warning level for the fire was reduced Saturday, the Country Fire Service said it was still a risk to lives and property.

New South Wales Rural Fire Service Deputy Commissioner Rob Rogers warned the fires could move "frighteningly quick." Embers carried by the wind had the potential to spark new fires or enlarge existing blazes.

"We are unfortunately very likely to lose homes but we will be very happy and call it a success if no lives are lost," he said.

Rural Fire Service Commissioner Shane Fizsimmons said the 264,000-hectare — 652,000-acre — Green Wattle Creek fire in a national park west of Sydney had the potential to spread into Sydney's western suburbs.

More than 130 fires are burning in New South Wales and at least half of those are out of control. A total of 48 fires were burning in Victoria state and conditions are expected to worsen with a southerly wind change.