Independence fire crews spent most of Monday working to ensure that an empty elementary school destroyed in a two-alarm fire was rendered safe.;;Fire broke out early Sunday at the former Anderson Elementary School, 9701 E. 35th St. It took fire crews several hours to put out the blaze.;;A few hot spots remained Monday, which prevented fire investigators from entering the building, said Tom Gentry, Independence police spokesman.;;The cause of the fire remains unknown. No damage estimates were available.