NSW bushfire started by army 'a side effect' Drone footage has been released showing residents and fire crews battling bush fires around the town of Lithgow. Courtesy CiviDrones/YouTube Firefighters back-burn near Lithgow to try to prevent the spread of the State Mine fire, which was started by Defence. Picture; John Grainger A MASSIVE fire started in the NSW Blue Mountains by a Defence training exercise was clearly unintentional, the Rural Fire Service says. The RFS yesterday revealed an investigation had found a Defence training exercise was responsible the blaze, which has burnt out more than 46,000 hectares near Lithgow and sparked fears of a "mega-fire." Defence will today be provided with a copy of the RFS report into the State Mine blaze and the federal government says it's taking the findings very seriously. Defence has launched its own investigation into the cause of the blaze. The RFS investigation found explosives training on army land at Marrangaroo on October 16 was responsible for starting the fire, which is still burning. Blue Mountains mayor Mark Greenhill says the fires have done significant damage to his community and has demanded an explanation from the army as to why the explosives exercise went ahead on a dry and windy day. But RFS Commissioner Shane Fitzsimmons says Defence is a "partner" in firefighting on many occasions, and he understands the fire was a side effect. "It wasn't deliberate, it was a side effect of a routine activity ... and clearly there was no intention to see fire start up and run as a result of that activity," he told reporters. He said Defence "worked intimately" with local bushfire committees and authorities on bushfire management across NSW. "They (Defence) have been fully co-operative from the outset," Mr Fitzsimmons SAID. There was no conspiracy here. Acting Defence Minister George Brandis says he's spoken to the Acting Chief of the Defence Force, Air Marshal Mark Binskin, about the matter. "The Australian government and the Australian Defence Force take this issue very seriously and continue to fully cooperate with the New South Wales authorities, including the New South Wales Police, who are investigating the fire," Senator Brandis said in a statement. Mr Fitzsimmons also said it was "so disappointing" that two eight-year-old boys had been caught by police trying to light a fire at East Maitland on Wednesday night. "As a parent myself I don't get it," he said. Lighting fires is a crime no matter your background, no matter your age, no matter your location. The fire commissioner also defended the RFS approach to the extreme fire danger yesterday. Hundreds of people left the Blue Mountains on the advice of the RFS, which warned if they weren't fully prepared to defend their homes from fire they should leave. However no homes were lost yesterday. "I would much rather be sitting here today copping criticism no matter how invalid I think they are, for doing what we thought was the right thing," Mr Fitzsimmons said. You cannot ignore the gravity of what was presented. There were 65 bushfires burning across the state on Thursday morning, with 24 uncontained. Still of concern were three fires in the Blue Mountains - at Springwood, Lithgow and Mt Victoria - as well as the blaze burning near Balmoral, in the southern highlands. There were more than 1000 firefighters still out in the field. The RFS could begin standing down some interstate crews today. However Mr Fitzsimmons said the fire situation across NSW was still "very dynamic" with high winds to peak around noon. But cooler conditions brought by a southerly airstream would probably continue until Tuesday or Wednesday next week, before hot conditions and norwesterly winds returned.