The 8,900-pound device created temperatures at ground zero which reached 5,400 degrees and generated the explosive power of 12,500 tons of TNT. All but 6,000 of the city’s 76,000 buildings were destroyed by fire or blast. The Japanese afterwards claimed that around 20,000 military personnel and 110,000 civilians died immediately. Though no statistics are conclusive, this estimate is almost certainly exaggerated. Another guesstimate, around 70,000, seems more credible.
