The bombing
How many people were killed by the atomic bomb that was dropped on Hiroshima?
Atomic bombings of Hiroshima and Nagasaki
Hiroshima was the primary target of the first nuclear bombing mission on 6 August, with Kokura and Nagasaki as alternative targets. The 393d Bombardment Squadron B-29 "Enola Gay", piloted by Tibbets, took off from North Field, Tinian, about six hours' flight time from Japan. The "Enola Gay" (named after Tibbets' mother) was accompanied by two other B-29s. "The Great Artiste", commanded by Major Charles Sweeney, carried instrumentation, and a then-nameless aircraft later called "Necessary Evil", commanded by Captain George Marquardt, served as the photography aircraft. After leaving Tinian the aircraft made their way separately to Iwo Jima to rendezvous with Sweeney and Marquardt at 05:55 at , and set course for Japan. The aircraft arrived over the target in clear visibility at . Parsons, who was in command of the mission, armed the bomb during the flight to minimize the risks during takeoff. He had witnessed four B-29s crash and burn at takeoff, and feared that a nuclear explosion would occur if a B-29 crashed with an armed Little Boy on board. His assistant, Second Lieutenant Morris R. Jeppson, removed the safety devices 30 minutes before reaching the target area. During the night of August 5–6, Japanese early warning radar detected the approach of numerous American aircraft headed for the southern part of Japan. Radar detected 65 bombers headed for Saga, 102 bound for Maebashi, 261 en route to Nishinomiya, 111 headed for Ube and 66 bound for Imabari. An alert was given and radio broadcasting stopped in many cities, among them Hiroshima. The all-clear was sounded in Hiroshima at 00:05. About an hour before the bombing, the air raid alert was sounded again, as "Straight Flush" flew over the city. It broadcast a short message which was picked up by "Enola Gay". It read: "Cloud cover less than 3/10th at all altitudes. Advice: bomb primary." The all-clear was sounded over Hiroshima again at 07:09. At 08:09 Tibbets started his bomb run and handed control over to his bombardier, Major Thomas Ferebee. The release at 08:15 (Hiroshima time) went as planned, and the Little Boy containing about of uranium-235 took 44.4 seconds to fall from the aircraft flying at about to a detonation height of about above the city. "Enola Gay" traveled before it felt the shock waves from the blast. Due to crosswind, the bomb missed the aiming point, the Aioi Bridge, by approximately and detonated directly over Shima Surgical Clinic at . It created a blast equivalent to , ± 2 kt. The weapon was considered very inefficient, with only 1.7% of its material fissioning. The radius of total destruction was about , with resulting fires across . People on the ground reported seeing a "pika" or brilliant flash of light followed by a "don", a loud booming sound. Some 70,000–80,000 people, of whom 20,000 were soldiers, or around 30% of the population of Hiroshima, were killed by the blast and resultant firestorm. and another 70,000 injured.