Firefighters hose down hot spots after a fire destroyed the loading ramps at the old Swift slaughterhouse and packaging plant in Ogden early Tuesday. "We don't know the cause of the fire," said Ogden Fire Chief Joseph Murray. About 40 firefighters were summoned at about 4:30 a.m. to fight the blaze, and Murray said the fire was under control two hours later. There were no reported injuries. Murray said he suspected the fire was caused by transients who went into the loading docks and started a fire to keep warm. He estimated damage to be about $75,000. The building, located in west Ogden right off the 24th Street viaduct, is now used as a warehouse for Smith and Edwards. The fire was contained to the loading docks. The five-floor, metal-framed structure was used to load cattle into the brick building for slaughter.