After the bombs fell on Hiroshima and Nagasaki there was utter devastation – The blast demolished two thirds of the buildings in Hiroshima, and the firestorm burnt everything within a 4.4 mile radius of the epicentre of the blast.
After the bomb was dropped on Hiroshima, black rain fell after 30 minutes, which was radioactive.
Actual footage following the aftermath of the Atom Bomb blast, 6 years later.
Film from 1983 that depicts The Day After.