It is feared bushfires raging in Australia's New South Wales could merge and form one massive blaze. A state of emergency has been declared as firefighters continue to battle the flames.
More than 200 homes have been destroyed in the Blue Mountains.
Reporter Jonathan Samuels is monitoring events on the outskirts of Sydney:
Crews have been battling fires that flared in high winds and searing heat across the state of New South Wales last week.
Firefighters continue to battle large blazes
While dozens of blazes have been contained, 58 were still alight and 14 of them out of control, enveloping Sydney in a thick white smoke haze that prompted warnings for people to stay indoors and avoid exercising.
The main area of concern was near the town of Lithgow, west of Sydney, where a huge fire that has already burned nearly 40,000 hectares (99,000 acres) was threatening the communities of Bilpin, Bell, Clarence and Dargan.
Officials fear intensifying heat and winds this week could push it into another blaze at nearby Mount Victoria in the Blue Mountains and then move towards the populated areas of Katoomba and Leura.
"I don't think I've ever used the word mega-fire," said New South Wales rural fire service commissioner Shane Fitzsimmons.
"But the reality is that the modelling indicates that there's every likelihood that in the forecast weather conditions that these two fires, particularly up in the back end of the mountains, will merge at some point."
Army admits it could be responsible
The Australian military is investigating whether it was responsible for starting the blaze, northwest of Sydney.
The Australian Defence Force said its personnel were carrying out explosive ordnance training in the area on Wednesday, the day the blaze started.
Amid the worst fire disaster in the state for nearly 50 years, New South Wales declared a state of emergency on Sunday, which gives firefighters the power to forcibly evacuate people, with penalties for refusing.
Emergency Services Minister Mike Gallacher said every possible resource was being used, including firefighters being drafted in from interstate and the possibility that the military could also be deployed.
"Everything is being thrown at this, I can assure you," he said.
Looters are 'scumbags'
With hundreds of people evacuated due to the encroaching flames, police revealed Monday they were dealing with reports of looting from victims, although the number of incidents was small.
State Premier Barry O'Farrell called looters "scumbags" and vowed to track them down.
Helicopters are being used to try extinguish the flames
"I'm just appalled that at these critical times, when people have been evacuated from homes or whether people have left homes because of fire dangers, that other scumbags in the community would front up and seek to rob them," he said.
Emergency services monitor the fires carefully
Police, meanwhile, said a young boy, reportedly aged 11, was being questioned about deliberately lighting a fire on the New South Wales Central Coast last week that forced hundreds of people to flee their homes and saw the closure of Newcastle airport.
Social media users have been sharing their photographs of the fires:
@Newstalkfm it's very scary this was the smoke cloud above the city #nswfires pic.twitter.com/4JhAeKe6zg
— Hannah Fraser (@EI_hfraser) October 19, 2013
Buena Vista Rd in Winmalee was one of the worst hit: over 40 homes destroyed. @abcnews @702sydney #NSWfires pic.twitter.com/IsPyk3GUNF
— Mohamed Taha (@Mo_Taha1) October 21, 2013
Backburning near Lithgow Workers Club (an evac point for locals + pets). A campfire compared to Thurs ... #nswfires pic.twitter.com/8SM95XtQD4
— ClubsNSW (@ClubsNSW) October 21, 2013
The #Sydney sky is surreal. The Blue Mountains bushfires must be huge. #nswfires pic.twitter.com/KC9KUDTxfv
— Damon Meredith (@DamonAM) October 17, 2013
Bird's eye view: snapped this flying in over the Southern Highlands and Illawarra this morning. #nswfires pic.twitter.com/uBB4zIAk8P
— Stuart Howie (@StuartJHowie) October 21, 2013
