Ghastly masks

When I was looking for some mask inspiration I came upon this photo ~ really creepy! Unfortunately there was no information with the photo, so all I can surmise is that it was taken during wartime ~ looks like a large group of children wearing gas masks ~ maybe a youth group of sorts? Notice that everyone is dressed in what looks to be a school uniform ~ except the troop leaders. Odd and disturbing, but mesmerizing.... almost looks like a parade ~ but why would they be celebrating?

{photo found here}