NSW Emergency Services Minister David Elliott has described the deliberate lighting of a bushfire which destroyed 21 homes in the state's north as "a bastard act".

Key points: Fires ravaged more than 100,000 hectares of land in northern NSW yesterday

Fires ravaged more than 100,000 hectares of land in northern NSW yesterday Police are urging families who want to find loved ones in the area to call 1800 228 227

Police are urging families who want to find loved ones in the area to call 1800 228 227 Authorities have described the most destructive fire, which started late Friday as "suspicious"

Four separate blazes ripped through several areas in northern NSW yesterday, with much of the damage in the areas of Rappville and Ewingar.

NSW Rural Fire Service (RFS) superintendent Michael Brett said initial investigations indicated that blaze, which started on Friday night, was "suspicious".

"We have identified suspicious activity in that area," he said.

Local police will lead the investigation, and be assisted by the State Crime Command's arson squad.

"It really is a bastard act if you are going to put your own community at risk," Mr Elliott said.

"If that has been proven to be the case that will be handed over to police and charges I'm sure will be laid."

All that remains of one Ewingar property. ( ABC News: Catherine Marciniak )

NSW Police Superintendent Toby Lindsay said "significant prosecution" would be pursued.

"And anyone who has information is urged to provide that to Crime Stoppers ... it may be the last piece of the puzzle we need to take action," he said.

Appalling weather conditions yesterday meant fires flared and burnt through thousands of hectares of land.

The village of Rappville was hit hard, and despite widespread destruction there are no confirmed fatalities.

NSW Police officers are still searching buildings and trying to reunite families.

Bianca Bowman, from community group Our Two Hands, said people were in shock.

"We have got people who have had really rough lives who have lost literally everything," she said.

15 homes were destroyed in Rappville. ( ABC News: Matt Coble )

The RFS suspects more properties have been lost in the Ewingar area, near Tenterfield.

"We're working very hard to get that as quickly as possible and we know people are waiting for that news," RFS Deputy Commissioner Rob Rogers said.

"But we want to give them the correct news."

Superintendent Brett said some firefighters had told him yesterday's conditions were among the worst they had seen.

Emergency warnings were issued for four separate bushfires yesterday, that were all within 100km of each other.

However, favourable weather conditions today have meant the threat to properties has eased.

The property in Rappville was reduced to rubble. ( Facebook: Casino Golf Club )

Robert Mustow, the Mayor of Richmond Valley Council which covers the Rappville area, said he was "broken" by the devastation.

"My heartfelt feelings go out to the whole community," he said.

"There's a big mill out there that's burnt out. It's a loss of employment not only for Rappville but for the Casino community, too.

"Yesterday the winds were ferocious and people said it was like Armageddon."

Prime Minister Scott Morrison said his thoughts were with those whose homes had been destroyed.

"For those communities around Casino, it's going to be a very tough day but know that Australians are with you," he said.

There are two emergency evacuation centres available for residents — one at Woodburn Memorial Hall in Woodburn and another at St Mary's College in Casino