The Battle of Los Angeles

http://en.wikipedia.org/wiki/Image:La_air_raid.gif

In the early morning hours of Feb. 25, 1942, someone reported a mysterious object flying over Southern California, and L.A. briefly went nuts. A blackout was ordered, sirens were sounded, and the military fired more than 1,400 anti-aircraft shells into the night sky. Some said they struck the object; certainly they struck several buildings, and killed three civilians.

No one knows what really happened that night. The object could have been a weather balloon, a blimp, a Japanese fire balloon, or nothing at all. Navy secretary Frank Knox chalked the whole episode up to war nerves. With three local residents dead of heart attacks, that seems as good an explanation as any.