gogh and edwest2 many thanks for your comments!
More information concerning the photo as requested below:
RKKA stands for Workers' and Peasants' Red Army, East Prussia was the main part of the region of Prussia along the southeastern Baltic Coast.
This photo was taken on Industriewerk Heiligenbeil GmbH plant located in the city of Heiligenbeil.
An author of this photo was someone from 1st Air Army of the Soviet Airforce.
Best regards,
Alexander