A man killed himself at Burning Man-style arts festival by leaping into a towering burning art structure in front of hundreds of horrified onlookers, authorities and witnesses said. On Monday, scores of "burners" - who commune in the Nevada desert every August for Burning Man -were mourning the doomed festivalgoer after he dove into the flames during a moonlit bonfire ritual at the Element 11 fest near Salt Lake City late Saturday.