The terrifying moment firefighters sprinted away from a wall of flames has been captured on camera, as NSW continues to be ravaged by several out-of-control blazes.

Firefighters from NSW Fire and Rescue's Station 79 were dousing flames at Orangeville last night, about 70km from Sydney's CBD.

The NSW Rural Fire Service (RFS) issued an emergency warning for the blaze, which was threatening properties on the doorstep of Australia's biggest city.

As embers rained down on crews, one firefighter captured the moment flames leapt into treetops.

As the danger intensifies, the crew can be seen sprinting to safer ground.

Key points: NSW's bushfire crisis intensified on Thursday, with several emergency warnings issued

NSW's bushfire crisis intensified on Thursday, with several emergency warnings issued Fire danger conditions are rated "severe" in several areas on Friday

Fire danger conditions are rated "severe" in several areas on Friday More than 680 homes have been destroyed by fires in NSW this season

That blaze, dubbed the Green Wattle Creek fire, was one of seven the RFS issued emergency warnings for Thursday afternoon.

Local Scott Bruce lives in the area and stayed to protect his home.

Sprinklers surrounded his house, two trailers held water pumps and a generator back-up was on standby to help pump water from his home's tank.

Scott Bruce stayed behind to protect his home and property from the Wattle Creek fire. ( ABC News )

Mr Bruce said goodbye to his wife and children who left for safer ground.

He said he watched the blaze jump a nearby valley, but it wasn't the moving flames that worried him most.

"It's not so bad when you see the glow," Mr Bruce said.

"It's when those embers start dropping that you wonder where a spot might start."

Embers rain down from the Three Mile Creek fire on Thursday. ( ABC News: Kathleen Calderwood )

Sydney surrounded by flames

Major bushfires continue to rage around Greater Sydney with at least six blazes burning at the edges of Australia's most populous city.

Several bushfires were burning at emergency level on Friday.

A fire burning at Three Mile Creek in the Hawkesbury and Central Coast region was particularly difficult for firefighters overnight, impacting Mangrove Mountain.

The frontline of the Wollondilly fire, which is moving towards Orangeville. ( ABC News: Selby Stewart )

To the west, the Gospers Mountain fire continues to burn over a large area around Wollemi National Park, which crossed Putty Road south of Colo Heights overnight. It has lashed 250,000 hectares of land so far.

On the state's south coast, the vicious Currowan fire in Shoalhaven ripped through multiple buildings, leaving a path of destruction in its fiery wake.

Sydneysiders woke on Friday morning to ashen debris that had rained down overnight from the blazes, coating gardens and decks in the blackened remains of bushland.

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Total fire bans were in place on Friday in 10 regions across the state, including Greater Sydney, the Illawarra, the Central Ranges and Greater Hunter.

Forecaster Rebecca Kamitakahara from the Bureau of Meteorology said the weekend could bring some relief, with winds turning on shore and coming in from the east.

The RFS welcomed the arrival of 21 Canadian fire management personnel on Thursday, here to help fight fires across the state.

The 21 Canadians are trading in their Christmas to help the hundreds of thousands of Australians still at risk from this year's unprecedented bushfire season.