By August 1945, the Manhattan Project built three nuclear fission weapons. Two of these bombs were used by the United States to attack the cities of Hiroshima and Nagasaki in Japan. People from the Manhattan Project believe that around 105,000 people were killed and 94,000 were hurt when the bombs were used. Medical professionals later came to believe that more than 225,000 people died when everyone affected after long periods of time are counted. Japan announced its surrender after the atomic bombings of Hiroshima and Nagasaki.