(Hillsboro, OR)  --  Authorities believe the weight of a blanket of snow that had fallen on a warehouse in Hillsboro caused its roof to cave in yesterday morning.  The Hillsboro Fire Department said the eight-thousand-square-foot warehouse on Southeast 4th suffered a total roof collapse while five people were in the building.  KOIN-TV reports three men and two women were uninjured but soaked from the flooding caused by the broken fire sprinkler pipes.