The atomic bomb destroyed or seriously damaged nearly 60,000 of Hiroshima's 90,000 buildings, accounting for more than 67 percent of the city's structures. All utilities and transportation services in Hiroshima were affected for varied durations of time. The nuclear blast also caused extensive damage to much of the surrounding countryside. After the war, American authorities estimated that the destruction caused by the bombing was greater than that caused by any other military operation up to that time. In fact, it was probably equal to that caused by all previous wars combined. The atomic bombing of Hiroshima and Nagasaki killed approximately 140,000 people, making it the deadliest single incident at sea or in air in history. It is estimated that about 80,000 people died immediately, with another 20,000 dying as a result of their injuries over a period of several months. The number of buildings destroyed in Hiroshima has been a subject of debate. Some sources estimate that between 50,000 and 70,000 buildings were destroyed, while others put the figure much higher at around 200,000. In April 1995, a group of Japanese architects issued a statement claiming that there were more than 60,000 buildings destroyed or severely damaged by the bombing. They based this claim on an analysis of photos taken after the attack. However, this figure has been disputed by other experts in nuclear physics and city planning.