Tony Abbott has taken a tumble as he stepped out of a fire truck to help battle a bushfire in Sydney’s north.

The former Prime Minister and volunteer firefighter joined crews at Castle Cove where the blaze broke out on Saturday morning.

Abbott received a 10-year service award in 2015 from the NSW Rural Fire Service.

Two major bushfires were last night threatening homes in the New South Wales Hunter region, with authorities warning some residents it was too late to leave.

Abbott falls after arriving at Castle Cove. Photo: AAP

The fast-moving fire at Cessnock was burning on several fronts, with fire crews working to slow the spread of the blaze in the areas of Kearsley and Aberdare.

The ABC reported that a thermal imaging aircraft flew over the fire as authorities attempted to track its movement and size.

An emergency warning was in place for the fire and Rural Fire Service spokesman Paul Best said residents needed to make a clear decision about whether they would stay or leave their homes.

“If they have chosen to stay they should be out actively defending their property, looking out for spot fires,” he said.

“If they don’t feel comfortable staying or they want to leave, the best time to leave is while the path is clear.

“It’s really important that decision is not left to the last minute.”

An evacuation centre has been set up at Cessnock’s basketball stadium for locals who have been forced to leave their homes.

Properties under ember attack

An emergency warning was also in place for another fire burning at Balickera, north of Raymond Terrace that has forced the closure of the Pacific Highway in both directions.

The blaze was heading towards the village of Limeburners Creek and the Rural Fire Service warned homes were at risk.

A Skycrane drops water at Castle Cove. Photo: AAP

Emergency telephone warning messages have been sent to homes and mobile phones in the area.

Residents around The Bucketts Way have been told it is too late to leave their homes and have been urged to take shelter to protect themselves from the fire.

Mr Best said authorities had been battling dry, windy conditions all day.

“The fire is starting to burn toward some isolated rural properties and there are some properties under ember attack,” he said.

“There are a lot of firefighters that are in and around that fire ground and they are also being supported by water bombing aircraft.

The blaze threatening Cessnock. Picture: Lily Benson

“They are working hard in extremely difficult conditions to try to get control over that fire.”

More than 200 firefighters were last night fighting the fires in the lower Hunter region.

Residents were being urged to stay up to date with the bushfire situation thoughout the evening.

A 16-year-old has been charged for starting a bushfire at Cranebrook that damaged a house and destroyed a car and shed.