History: Atomic Bombing Of Hiroshima, Japan

The radius of total destruction was about a mile (1–2 km), followed by fires across the northern portion of the city to two miles (3 km) south of the bomb.
One American POW, Joe Kieyoomia, was in Nagasaki at the time of the bombing but survived, reportedly having been shielded from the effects of the bomb by the concrete walls of his cell.
An unknown number of survivors from the Hiroshima bombing had made their way to Nagasaki, where they were bombed again.
The Mitsubishi-Urakami Ordnance Works, the factory that manufactured the type 91 torpedoes released in Pearl Harbor, was destroyed in the blast.