A long lost image from the Hiroshima atomic bombing has been discovered at a Japanese elementary school.

The black-and-white photograph shows the mushroom cloud over Hiroshima split into two distinctly separated parts, one on top of the other.

The rare image was found at the Honkawa Elementary School in Hiroshima city, in a collection of about 1,000 articles on the WWII atomic bombing. The material was donated by a late survivor, Yosaburo Yamasaki, in or after 1953.

According to the Japanese daily Asahi Shimbun, a memo on the back of the photo says it was shot near the town of Kaitaichi, some six miles east of ground zero, two minutes after the bomb was dropped on August 6, 1945.

The book reported that the photographer is “unknown” and that the image was shot “20-30 minutes” after the bombing.

More: Rare Photo of a-Bomb Cloud Found in Hiroshima : Discovery News