The fire is believed to have been started on June 25 by a lightning strike. As of Aug. 19, the Tetlin Junction Ridge Fire had grown to 76,548 acres in size [ http://inciweb.nwcg.gov/incident/3459/ ] and was 50 percent contained.
National Geographic reports fire tornados are a rarely documented phenomenon, though they are believed to occur somewhat frequently.
Watch the Alaskan 'firenado' in the video above -- skip to 1:34 to see it -- and learn how fire tornadoes occur by watching the clip below.