'Too late to leave': Bushfires at Nowra labelled 'suspicious'

Firefighters have gained the upper hand against a bushfire that raged toward homes on the NSW south coast with the help of waterbombing aircraft.

The Rural Fire Service issued an emergency warning after 12.30pm on Monday saying to residents in West Nowra: "People are advised to take shelter as the fire front approaches".

There are more than 150 firefighters currently protecting properties on the ground. Source: 7 News

Several fires burned and the RFS advised residents it was too late to leave.

But Thor, the large air tanker, began reigning the blaze in, even as dry and windy conditions made battling the fire problematic on the ground.

Firefighters on the ground are being supported by aircraft to protect properties in the area. Source: 7 News

"It was very dark black gloomy looking smoke but that big thing came in and knocked it over quickly," RFS commander John Dun told Fairfax Media.

The fires are being treated as suspicious after RFS crews spent much of the weekend extinguishing three separate blazes.

"Thank goodness for the wonderful volunteers at the NSW RFS whose hard work means my neighbours and I should have homes to go home to tonight," one resident posted on Facebook.

Meanwhile, another bushfire broke in the Royal National Park, south of Sydney, and was declared out of control.

The RFS was responding to more than 100 fires across the state as evening fell on Monday.

Multiple bushfires are burning out-of-control on NSW's south coast, with the Rural Fire Service telling residents near West Nowra to take shelter.

It issued an emergency warning after 12.30pm on Monday saying: "People are advised to take shelter as the fire front approaches".

The warning was updated at 2.36pm, with the RFS saying multiple fires are moving in a North Easterly direction and are currently out of control.

Several fires are burning near Filter Rd and Cavanagh Lane, West Nowra and it's too late for residents to leave, the RFS says.

The NSW Rural Fire Service said on Twitter earlier on Monday that the fires in West Nowra are being treated as suspicious.

Residents in the vicinity of Filter Road, Depot Road, West Street, Bainbridgge Crescent, Shoalhaven Street and Plunketts Street in West Nowra should take shelter as the fire front approaches.

"Under these conditions, fires are uncontrollable, unpredictable and fast-moving. Embers will be blown up to 4km ahead of the fire, creating spot fires that will move quickly and in different directions," the RFS said.

"These spot fires may threaten your home earlier than the predicted main fire front."

According to the NSW Rural Fire Service the fires are currently moving in a North Easterly direction. Source: 7 News

There are now more than 150 firefighters now on the ground, the NSW Rural Fire Service said in its latest update.

Thor, the large air tanker has been deployed to assist firefighters who are working to protect properties in the area but are battling hot, dry and windy conditions.

The NSW Rural Fire Service says the fires are moving in a North Easterly direction. Source: @NSWRFS/ Twitter

"Erratic fire behaviour at West Nowra. Avoid (the) area completely unless you need to be there," NSW RFS deputy commissioner Rob Rogers tweeted.

According to the local newspaper South Coast Register, RFS crews were called out on three occasions to extinguish fires off Filter Road at the weekend.

Parts of the area has been evacuated, including an Echidna Early Learning Centre .