On May 6th, 1937, the German airship Hindenburg had just completed its 21st crossing of the Atlantic. While approaching it's landing field in Lakehurst, New Jersey, it burst into flames and crashed, killing 35 people aboard. Ironically, 33 of the victims died from injuries sustained while jumping from the airship, not from the resulting fire.
The airship exploded because it was filled with explosive hydrogen gas, rather than the safer but vastly more expensive helium. This disaster effectively ended the era of airships.