No one knows exactly what caused the first small flame in the southwestern corner of the main circus tent in Hartford, Connecticut, on July 6, 1944, but partially obscured by the bleachers, it quickly grew before bursting forth during a packed show on a hot summer day. Karl Wallenda, whose family of trapeze artists were performing under the Big Top, was one of the first to see it, and his reaction prompted Bandleader Merle Evans to play "Stars and Stripes Forever", the universal circus disaster signal. Ushers attempted to extinguish the flame, but the tent had been meticulously waterproofed with paraffin soaked in gasoline, and the entire tent burst into flames within seconds.