I came across this fact while reading a kid's book about WWII. http://en.wikipedia.org/wiki/Fire_balloon

From the above wikipedia article:

"On May 5, 1945, a balloon bomb that had drifted over the Pacific killed five children and a woman. It exploded when a 13-year-old girl (Joan Patzke) attempted to pull the balloon from a tree during a church group picnic in the woods near Bly, Oregon."

Strange that this part of history has not had more coverage especially with the cover-up of it during much of the time is was happening in late 1944 through 1945.