 Some of his images were among the photos that were distributed to news media with the announcement of the first atomic bomb and the secret project that created it . In the weeks before the bombing of Hiroshima and Nagasaki in August 1945 , prints of 18 of his photographs were made in secrecy in preparation for the announcement . The photographs were declassified and distributed as part of the press kit . He also processed film taken by the damage assessment teams in his laboratory in Oak Ridge . It took three days to print them . Armed guards outside the darkroom . 
