On The 70th Anniversary Of The Bombings, See Hiroshima And Nagasaki Then Vs. Now
At the time, none of them knew anything. The radio, telephone, and telegraph in Hiroshima had gone dark. That was all the information the members of the Army General Staff in Tokyo had. And it was met only with confusion. Then, as strange, scattered reports surfaced, concern crept in. So, a small crew was dispatched to Hiroshima to survey the area and report back. After three hours of flying, and still about 100 miles from the city, they noticed the cloud of smoke.
The destruction heralded by that cloud of smoke can hardly be grasped with statistics or torrents of dire adjectives (the same, of course, goes for the bombing of Nagasaki three days later). Photographs probably can’t even truly do it. But these photographic comparisons of Hiroshima and Nagasaki then and now might be a start. See more at The Guardian.