In a menacing start to the warmer months, fire crews battled to save homes from fires at Llandilo, in Sydney's west, and Callala Bay, on the state's south coast.

A massive bushfire in Llandilo and Cranbrook burned ferociously for four hours, causing police officers to knock on doors and evacuate homes, two schools and a nursing home.

Some residents set up lawn sprinklers on their roofs while others had no time to grab pets or property before they fled.

Eventually, 200 firefighters from the Rural Fire Service and Fire and Rescue NSW were able to get the blaze under control at 6pm.

The crews were joined by several air tankers, which dumped water on the blaze and helped it quickly downgrade in severity.

At 3pm, the Rural Fire Service had issued an emergency warning, but the firefighting effort meant this was downgraded to Watch and Act an hour and a half later.

Areas worst-hit in Llandilo included Vincent Road, Sixth and Seventh Avenue, and Northern Road.

An eerie scene of charred trees, blackened ground, hazy smoke, fallen power lines and smouldering wooden fences were left behind as anxious homeowners stood on their driveways watching firefighters work in the late afternoon.

Two males, aged 17 and 21, were arrested near the fire on Vincent Road and were expected to be charged on Friday night with deliberately lighting the blaze.

The Rural Fire Service reported damage to a number of properties on streets bordering the blaze.

Two homes on Vincent Road, Cranebrook, were damaged by ember showers that set surrounding trees alight and got into roof cavities, RFS Commissioner Shane Fitzsimmons said.

There were no reports of injuries, but ambulances waited near the fire ground in case residents were overcome with smoke.

Photos from students at Xavier College in Llandilo showed black, billowing clouds looming down on the school oval as they evacuated.

Terrifying view from inside Xavier College as fire edged closer to school. Image taken by student from bus stop at the school.Posted by The Western Weekender on Thursday, 3 November 2016

The fire's intense heat partially melted some cars, and lit others on fire, including Mitchell McGregor's ute.

Mr McGregor had parked on the side of Vincent Road next to the Wianamatta Reserve and went with a friend to return hired landscaping equipment.

The 23-year-old soon received frantic phone calls.

"We've got everyone calling us saying 'everything's on fire," he said.

"Me and my mate, the ute was on fire and we were trying to get stuff out of it."

The pair managed to salvage a generator and a nail gun he bought on Friday morning, but the ute itself was burned beyond repair by the fast-moving blaze, which was fanned by wind.

"We [saw] it jump around 20 foot across the road and it started burning," Mr McGregor said. "It came down here way fast."

Ros Dolan, who lives further up Vincent Road, was driving home from work when the blaze was at its height. She stood on her porch with her son as investigators began to comb through Wianamatta Reserve on Friday evening.

Detectives from NSW Police and fire service arson investigators brought in a sniffer dog and led it through the reserve, while other investigators took photographs of the charred trees.

The blaze burned to the road's edge opposite Ms Dolan's house and ignited a spot fire at the side of her home. Down the road, a neighbour's car was hit by an ember attack.

"We were very lucky," Ms Dolan said. "My daughter's partner came over while it was roaring and grabbed hoses and started to fight it.

"The heat was so intense. The firies did an amazing job."

As the Llandilo fire was gradually brought under control, another emergency warning was issued for an out-of-control fire near the small community of Callala Bay, near Jervis Bay on the NSW south coast.

It came as the RFS issued its first total fire bans for the season on the north coast and far north coast.

Mr Fitzsimmons said NSW had seen a wet winter but Friday's fires were a worrying reminder that we are amid bushfire season.

"Clearly today is a reminder of just how quickly fires can spread when it's hot, its dry and it's windy," he said.

"We can't be complacent because we've had a really wet winter and lots of water around the state. What you saw this arvo, with warmer conditions, yes, it was a very high fire danger but we're only talking temperatures in the 30s."

Police remained on the scene in Llandilo on Friday night, directing traffic as firefighters mopped up after the blaze and ensured some trees which continued to smoulder were entirely extinguished.

Firefighters from the National Parks and Wildlife Service also attended the scene.

with Peter Hannam

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