On August 6, 1945, during World War II, an American B-29 dropped the atomic bomb over the Japanese city of Hiroshima. The explosion wiped out 90 percent of the city and immediately killed 80,000 people. Tens of thousands more would later die of radiation exposure. Three days later, another atomic bomb was dropped on Nagasaki, killing an estimated 40,000 people. Japan surrendered on August 15.