Key points:

Three people have died in bushfires in NSW

About 30 people are injured

At least 150 homes destroyed, the figure is expected to rise

Seventy-two fires burning across the state, 36 not under control

Conditions expected to worsen on Tuesday

Firefighters are currently using favourable conditions to try and control the fires already burning

A third person has been confirmed dead while several people remain missing as unprecedented bushfires continue to burn across NSW.

The body was found in a burnt-out building north of Taree after fire swept through the township of Johns River on Saturday afternoon.

The home was owned by a 63-year-old woman, but police are yet to confirm the identity.

The discovery brings the death toll to three, but authorities expect that figure to rise.

One person, believed to be an elderly man, was found in a burnt-out car in at the Kangawalla fire, near Glen Innes.

AAP

Firefighters discovered another woman in the same blaze who was treated for burns before being transferred to hospital where she later died.

The woman was 69-year-old Vivian Chaplain, who was trying to protect her home at Wytaliba, north-west of Coffs Harbour.

Authorities had put the number of missing at seven earlier in the day, but recent reports suggest it is now five, with NSW police saying only that "several" people remain unaccounted for.

"We can't rule out the really grave concerns that there could be more losses or indeed more fatalities as we get through and identify details across these fire grounds," NSW Rural Fire Service Commissioner Shane Fitzsimmons told reporters in Sydney.

Read more Emergency warnings in place for Noosa as Queensland bushfires worsen

At least 150 homes have been destroyed in the fires which have hit drought-ravaged areas.

More than 80 fires are burning across the state with more than 40 uncontained. One fire at Hillville in NSW and two in Queensland at Noosa and Cooroibah are at emergency warning level.

Morrison says army reservists could help

Prime Minister Scott Morrison said army reservists could be deployed "if necessary" to assist the firefighting effort.

While they aren't trained firefighters they could help create firebreaks away from the front or provide accommodation and logistical support, he told reporters.

Difficult firefighting conditions on the Hillville Fire, south of Taree. This is the fire burning near Diamond Beach. The fire is at Emergency Warning level. #nswrfs #nswfires pic.twitter.com/pJYWet1MEY — NSW RFS (@NSWRFS) November 9, 2019

"These fires have already claimed two lives ... and as we get access to further areas that have been cut off we are expecting worse news again," he said.

Mr Morrison earlier described the fires burning across Queensland and NSW as of Saturday morning as "simply terrifying".

Authorities have appealed to people to register themselves, and register details if they are concerned for missing loved ones.

Conditions are set to get worse with a dry and windy forecast showing no signs of let-up for firefighters and affected residents.

"Given the circumstances forecast for today which is a continuance of dry, windy conditions across an already very dry landscape there's every likelihood that we'll see fires increase in their alert level," said Mr Fitzsimmons.

The Red Cross says so far 1300 people have registered in eight evacuation centres across the state.

Glenn Innes Severn Council mayor Carol Sparks says her community has been "badly impacted" with the loss of two people and "many of our houses (and) our school."

"We are so impacted by drought and the lack of rain," she told AAP on Saturday.

"It's climate change, there's no doubt about it. The whole of the country is going to be affected. We need to take a serious look at our future."

Worst yet to come

Winds are expected to pick up in the afternoon and no rain is forecast throughout the weekend.

State Premier Gladys Berejiklian said the worst may be yet to come.

"We do need to brace ourselves and what is concerning is that the forecast weather conditions on Tuesday could mean that we're not through the worst of it," she told reporters at the press conference.

AAP

The blazes have resulted in "significant and widespread damage and destruction" to people, families, home-owners and the wider community with reports of damage to other buildings including a school which was destroyed, Mr Fitzsimmons said.

He said the fires battled on Friday - at one point fighting 99 fires, a record 17 of which were at emergency level all at once - had them in "uncharted territory", with seasoned firefighters of some 60 years experience saying they had never seen such conditions.

RFS Deputy Commissioner Rob Rogers said firefighters had dealt with "horrific" and "traumatic" scenes including helping people suffering with burns and some who had had heart attacks.

AAP

He told Nine News multiple blazes raging at the same time on Friday had left firefighters "torn between trying to send help to one fire, to another".

He said dozens of fires are still at risk of affecting properties on Saturday.

The fire at Glen Innes saw 164 inmates evacuated from Glen Innes Correctional Centre to Grafton Correctional Centre on Saturday morning due to bushfire risk to the prison, Corrective Services said.