Interesting random information I’ve found here.
20180607/https://en.wikipedia.org/wiki/1942
20180607/https://en.wikipedia.org/wiki/Battle_of_Los_Angeles
So, what happened here? With all the fear of war in their midst, once they saw a stray weather balloon, they mistaked it as an enemy Japanese aircraft, then proceeded to fire at it. With all the blitz about them, they were unaware that all the warfare was of their own side. No enemies involved.