Australia fires: NSW Blue Mountains fires 'could merge' 21 October 2013 Last updated at 05:27 Wildfires in Australia's New South Wales could merge to form a massive blaze, the fire commissioner said, as teams continued to fight fires across the state. Three fires near Lithgow, a city by the Blue Mountains, are thought to be at risk of merging into one fire front. NSW has been badly hit by bushfires after the hottest September on record. It has declared a state of emergency. Officials say conditions are likely to worsen this week. NSW Rural Fire Services Commissioner Shane Fitzsimmons said that the fire at State Mine in Lithgow was at risk of merging with the fire at Mount Victoria. "Modelling indicates that there's every likelihood under the forecast weather conditions that these two fires, particularly up in the back end of the mountains will merge at some point... there is every likelihood that these two fires will join up," he said. Bushfires in Australia Australia is often hit by bushfires during summer months from December to February. Causes can be lightening, arson, power-line arcing, dropped cigarettes or controlled burns that go wrong. On 7 February 2009 a prolonged heat-wave and dry spell led to the Black Saturday bushfires in Victoria. The fires became Australia's worst natural disaster, killing 173 people and burning thousands of houses. On 16 February 1983 almost 200 fires caused devastation across parts of Victoria and South Australia. Seventy-five people died in what became known as the Ash Wednesday fires. In January 2013, parts of NSW and Tasmania were hit by fires as temperatures soared to record levels, with average national temperatures topping 40 degrees Celsius. One person died in Tasmania and several hundred buildings were destroyed. He added that in a "worst-case scenario" the fire could merge with a third fire at Springwood but said: "With the continued success of the fire-fighting effort, let's hope that it doesn't extend all that far eastward." In a briefing on Monday morning, Mr Fitzsimmons said that 58 blazes were still burning, with 14 out of control. NSW declared a state of emergency on Sunday, allowing emergency services to order mandatory evacuations, and cut gas and power supplies if needed. "While it may cause distress, I would rather be apologising for inconvenience than dealing with devastation and despair," Mr Fitzsimmons said. Caroline Russell from Winmalee, in the Blue Mountains area, told the BBC that she had seen the fire move closer and closer to her home over the past few days. We were quite worried initially. What we thought was back burning seemed to get out of control. That's when we saw the water bombers come over," she said. The fire brigade say we're in no immediate danger at the moment but we should keep a watch on the situation. We're constantly monitoring it. Exhausted firefighters Fire fighting efforts are set to continue this week, with weather conditions expected to be the most challenging this Wednesday, with warm weather and strong winds predicted. "The challenging aspect of the forecast is that they're forecasting a strengthening of winds for Wednesday now, only by another 10km/h (6mph), but that's still going to be quite problematic," Mr Fitzsimmons said. Hundreds of people have been left homeless by the bushfires. Australia's military is investigating whether a training exercise using explosives may have started the State Mine bushfire. On Monday, an 11-year-old boy in the Port Stephens area was arrested on suspicion of deliberately lighting two fires on 13 October. One of the fires, at Heatherbrae, led to Newcastle Airport being shut and forced hundreds of people to evacuate, local reports said. With hundreds of houses already destroyed disaster welfare centres have been set up where families can start the planning needed to rebuild their lives, the BBC's Jon Donnison, who is near the community of Winmalee in the Blue Mountains, reports. Most of the firefighters are volunteers - many look exhausted, and some have even lost their homes, our correspondent adds.