Combat Strike Operations Order 35
509th Composite Group U.S. Army Air Force

Taking off from Tinian island at approximately 2:45 a.m. with Colonel Paul Tibbets as command pilot of the ‘Enola Gay‘, the B-29 ascended to operational altitude as it flew to Iwo Jima island to rendezvous just before 6:00 a.m. with the accompanying observation and photography aircraft

At 08:09, Colonel Tibbets started his bomb run over Hiroshima and handed control over to his bombardier, Major Thomas Ferebee.
The release at 08:15 went as planned, and the gun type atomic bomb containing about 141 pounds of uranium-235 took 44.4 seconds to fall from the aircraft flying at about 31,000 feet to a detonation height of about 1,900 feet above the city.

Due to a crosswind, the bomb missed the aiming point, the Aioi Bridge, by approximately 800 feet and detonated directly over Shima Surgical Clinic with the force equivalent to 16 kilotons of TNT.
The radius of total destruction was about 1 mile, with resulting fires across 4.4 square miles.

Around 70,000 to 80,000 people, including 12 U.S. prisoners of war, were killed and another 70,000 injured.