58th, 73rd, and 313th Bombardment Wings hit the Toyokawa Arsenal the next day. On the night of 7 August, the 525th Bombardment Group dropped 189 tons of mines on several different sea targets. On 8 August, the 58th, 73rd, and 313th Bomb Wings dropped incendiary bombs on targets at Yawata in the southern island of Kyūshū. At the same time, the 314th BW hit an industrial area of Tokyo. The Japanese defenses were still effective enough to down four B-29s during the Yawata raid and three at Tokyo. Since there was still no official reaction from Japan, the Americans felt that there was no alternative but to prepare a second atomic attack. The plutonium bomb called "Fat Man" was loaded into a B-29 known as Bockscar (Martin-Omaha built B-29-35-MO serial number 44-27297, the name often spelled Bock's Car), named after its usual commander, Captain Frederick C. Bock. However, on this mission, the aircraft was flown by Major Sweeney, with Capt. Bock flying one of the observation planes. The primary target was to be the Kokura Arsenal, with the seaport city of Nagasaki as the alternative. Bockscar took off on 9 August, with Fat Man on board. This time, the primary target of Kokura was obscured by dense smoke left over from the earlier B-29 raid on nearby Yawata, and the bombardier could not pinpoint the specified aiming point despite three separate runs. So Sweeney turned to the secondary target, Nagasaki. There were clouds over Nagasaki as well, and a couple of runs over the target had to be made before the bombardier could find an opening in the clouds. At 11:00 am, Fat Man was released from the aircraft and after a long descent, the bomb exploded. The yield was estimated at 22 kilotons of TNT. Approximately 35,000 people died at Nagasaki from the immediate blast and fire. After releasing the bomb, Sweeney was forced to divert to Okinawa because of a problem with a fuel transfer pump, and because of the long flight with multiple bomb runs and circling for better weather. There was not even enough fuel left to fly to Iwo Jima. After refueling on Okinawa, the B-29 returned to Tinian. The Japanese Emperor ordered that the government accept the Allied terms of surrender at once. It took time for the full details to be worked out, and there was a very real danger that some elements