The first atomic bomb has been dropped by a United States aircraft on the Japanese city of Hiroshima.
President Harry S Truman, announcing the news from the cruiser, USS Augusta, in the mid-Atlantic, said the device was more than 2,000 times more powerful than the largest bomb used to date.
An accurate assessment of the damage caused has so far been impossible due to a huge cloud of impenetrable dust covering the target. Hiroshima is one of the chief supply depots for the Japanese army.
The bomb was dropped from an American B-29 Superfortress, known as Enola Gay, at 0815 local time. The plane’s crew say they saw a column of smoke rising and intense fires springing up.
more at the bbc
By the way, there is a very interesting discussion of the politics surrounding the dropping of this bomb, and the subsequent cold war and east/west relationships, over on Primate Diaries: Intimidating the Soviets: A Hiroshima Anniversary Memorial. It is a very interesting read.