West Sydney bushfire caused by arson: cops Fire officials in NSW say they hope to have a bushfire west of Sydney under control by today. A BUSHFIRE that destroyed a western Sydney home in Marsden Park earlier this week was deliberately lit, police say. "There are crime scene indicators that lead us to suspect arson activity," NSW Police Assistant Commissioner Alan Clarke told reporters on Friday. He was speaking following emergency services investigations into the four main bushfires that tore through western Sydney and the Blue Mountains this week. The investigations revealed that another bushfire in Winmalee, which has burnt through more than 1000 hectares of bushland, came after a backburning operation jumped containment lines. Deputy commissioner of the RFS, Rob Rogers, said a hazard reduction burn was carried out in Winmalee last weekend, but unforeseen winds caused the blaze to escalate on Tuesday. "The winds on that day did exceed forecasts," Mr Rogers told reporters. They were around 90km/h, and that tested control lines on that hazard reduction and it did escape. The blaze has now been contained. He said power lines falling onto trees were responsible for the bushfire near Windsor Rd. "Branches came off trees and brought down power lines, igniting grass in the area," he said. Mr Rogers said investigators had so far been unable to determine the cause of the fourth significant fire at Castlereagh.