Few pictures emerged from Hiroshima after the United States dropped an atomic bomb on the Japanese city, seven decades ago on Aug. 6, killing more than 100,000 people and leveling many of its structures.

Images of the resulting mushroom cloud over Hiroshima have become closely associated with the city’s name. A similar scene would unfold three days later in Nagasaki, when another bomb was dropped and killed tens of thousands more people.

A number of photographers who were in Hiroshima on that day, and especially in the weeks or months afterward, later recalled the apocalyptic devastation they witnessed and the difficulties of capturing such scenes. (The Hiroshima Peace Memorial Museum retains a list of photographers and dates when they made pictures.)

Among the most searing testimonies came from Yoshito Matsushige. The local newspaper photographer, who was in his early 30s, was about to head into work when the bomb dropped. “The world around me turned bright white,” he said. “I was bare from the waist up, and the blast was so intense, it felt like hundreds of needles were stabbing me all at once.”

His remarks were part of eyewitness accounts recorded and produced in part by public broadcaster NHK. Matsushige detailed how he not only survived the blast, but then got dressed, grabbed his gear and left home to get a sense of the destruction:

I thought I would go to either either the newspaper or to the headquarters. That was about 40 minutes after the blast. Near the Miyuki Bridge, there was a police box. Most of the victims who had gathered there were junior high school girls from the Hiroshima Girls Business School and the Hiroshima Junior High School No.1. they had been mobilized to evacuate buildings and they were outside when the bomb fell. Having been directly exposed to the heat rays, they were covered with blisters, the size of balls, on their backs, their faces, their shoulders and their arms. The blisters were starting to burst open and their skin hung down like rugs. Some of the children even have burns on the soles of their feet. They'd lost their shoes and run barefoot through the burning fire.
When I saw this, I thought I would take a picture and I picked up my camera. But I couldn't push the shutter because the sight was so pathetic. Even though I too was a victim of the same bomb, I only had minor injuries from glass fragments, whereas these people were dying. It was such a cruel sight that I couldn't bring myself to press the shutter. Perhaps I hesitated there for about 20 minutes, but I finally summoned up the courage to take one picture. Then, I moved 4 or 5 meters forward to take the second picture. Even today, I clearly remember how the view finder was clouded over with my tears. I felt that everyone was looking at me and thinking angrily, "He's taking our picture and will bring us no help at all." Still, I had to press the shutter, so I harden my heart and finally I took the second shot. Those people must have thought me duly cold-hearted.

Matsushige said he walked for hours that day, taking in various grisly scenes around the city, and spoke about finding scenes where “I couldn’t take the shot.” That night, he washed his film in a creek and hung it on a tree to dry. Five of his pictures would later be published.

In September 1952, Matsushige's work was published in the U.S. for the first time by LIFE magazine. A big feature, which noted that Japanese photographers had their pictures that day "suppressed by jittery U.S. military censors" for years, included scenes from both Hiroshima and Nagasaki.

LIFE detailed how photographers in Hiroshima “saw more than they could force themselves to photograph” and how “the worst scenes went unrecorded.” An unnamed photographer clarified that point:

Many times I tried to trip the shutter release but the victim would ask for pity … It was too cruel, too inhuman, to ignore their pleadings … If I had known it was an atom bomb, I don’t think I would have ever tried taking pictures.

Following images from Nagasaki by army photographer Yōsuke Yamahata, LIFE closed the article with this realization: “To a world building up its stock of atomic bombs, the people of the two cities warn that the long suppressed photographs, terrible as they are, still fall far short of depicting the horror which only those who lived under the blast can know.”

In the weeks after the bombings of Hiroshima and Nagasaki, photographer Bernard Hoffman traveled to those cities for LIFE to survey the destruction. Several of Hoffman’s images, not printed at the time, were published online a few years ago. Notes from Hoffman to his editor, Wilson Hicks, in September 1945 were also published, providing a grim glimpse into what he witnessed on assignment:

We saw Hiroshima today -- or what little is left of it. We were so shocked with what we saw that most of us felt like weeping; not out of sympathy for the Japs but because we were shocked and revolted by this new and terrible form of destruction. Compared to Hiroshima, Berlin, Hamburg, Cologne, are practically untouched ...
Only ten, steel-framed buildings still stand -- but there is nothing left of them too. They’re just blackened hollow shells; and like everything else in Hiroshima, they’re twisted. The sickly-sweet smell of death is everywhere…

Sgt. Joe O’Donnell, a Marine photographer, arrived in Japan three weeks after the bombings. He then began a months-long journey across the country -- using two cameras, one to take pictures for his own records -- documenting the damage for the American military.

After O’Donnell returned to the United States in 1946, he locked the negatives in a trunk and didn’t look again for decades. His account, laid bare in his book Japan 1945: a U.S. Marine’s photographs from Ground Zero, encompasses what the then-23-year-old witnessed while touring cities damaged by the blasts and air campaign. Here’s how he summed it up:

"The people I met, the suffering and struggles I witnessed, and the scenes of incredible devastation … caused me to question every belief previously held about my so-called enemies.”

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