Mitchell Recreation Area is a small picnic area near Bly, Oregon, United States. It is also known as Mitchell Monument. It is the only location in the continental U.S. where Americans were killed during World War II as a direct result of enemy action. The deaths were caused by a Japanese balloon bomb. The site is maintained by the United States Forest Service and is listed on the National Register of Historic Places.

From Wikipedia:

en.wikipedia.org/wiki/Mitchell_Recreation_Area

On May 5, 1945, a pregnant woman and five children were killed when they discovered a balloon bomb that had landed in the forest of Gearhart Mountain in Southern Oregon. Pastor Archie Mitchell and his pregnant wife Elsye (or Elsie) drove up to Gearhart Mountain with five of their Sunday school students (aged 11–14) to have a picnic, and Elsye and the children got out of the car at Bly, Oregon, while Archie drove on to find a parking spot. As Elsye and the children looked for a good picnic spot, they saw a strange balloon lying on the ground. As the group approached the balloon, a bomb attached to it exploded and Elsye and all five children were killed. Archie witnessed the explosion and immediately ran to the scene and used his hands to extinguish the fire on his wife's and the children's clothing, but he could not save them. These are the only known deaths caused by the balloon bombs, and also the only known deaths in the continental U.S. as the result of enemy action during World War II.

Military personnel arrived on the scene within hours, and saw that the balloon itself still had snow underneath it, while the surrounding area did not. They concluded that the balloon bomb had drifted to the ground several weeks earlier, and had lain there undisturbed until found by the group.

Elyse Mitchell is buried in the Ocean View Cemetery in Port Angeles, Washington. A memorial, the Mitchell Monument, is located at the point of the explosion, 110 kilometers (70 mi) northeast of Klamath Falls in the Mitchell Recreation Area. It was listed in the National Register of Historic Places in 2001. Several Japanese civilians have visited the monument to offer their apologies for the deaths that took place here, and several cherry trees have been planted around the monument as a symbol of peace.