This was no ordinary photo opportunity: After the atomic bomb was dropped on Hiroshima, 40 years ago today, Yoshito Matsushige wandered around his city for eight hours, carrying one of the few cameras that survived the bombing as well as two rolls of film with 24 possible exposures.

Matsushige, 33 years old, a photographer for Hiroshima's leading daily newspaper, lined up one gripping image after another: a woman nursing a dead baby, a streetcar filled with charred passengers still hanging on to their straps. But he could only bear to push the shutter five times.

When he was done, he returned home, about two miles from ground zero, and developed the pictures in the most primitive way, since every darkroom in the city, including his own, had been destroyed. Under a star-filled sky, with the landscape around him littered with collapsed homes and Hiroshima still smoldering in the distance, Matsushige washed his film in a creek and hung it out to dry on the burned branch of a tree.

These five photographs were apparently the only pictures taken in Hiroshima on that day. They are all the world will ever know about what Hiroshima looked like on Aug. 6, 1945. Only Matsushige knows what the 19 photos he didn't take might have looked like.

When the bomb exploded, Matsushige, a short, slim newspaperman, was eating breakfast. As the great white light flooded the room he immediately thought of the magnesium flash used by photographers. It was as if God himself was photographing the Earth.

Then Matsushige was blown across the room, the walls caved in and the roof fell. After a few minutes the smoke cleared and, he recalls, "Maybe my professionalism awoke." From the debris he dug out his hand-held camera and 6-by-6 film -- and suitable clothes to wear to work -- and left for the Chugoku Shimbun office.

Heading northwest, he crossed the river at the Miyuki Bridge, 1 1/2 miles from the hypocenter of the blast. Matsushige saw that a hellfire of flames up ahead would prevent him from proceeding. When he returned to the bridge he was surprised to find that it was filled with people. Some were already dead. A woman carrying a dead, blackened baby was walking about, calling its name. Matsushige retreated and framed a photo of this mother and child. He touched the button but could not push it.

"My injuries were not serious," he remembers, "and this scene was so atrocious. Most people were burned. I thought they would be enraged if someone took a picture." Twenty minutes later, Matsushige finally "gathered all my courage" and took the first picture taken in Hiroshima on Aug. 6.

The photograph shows a group of schoolchildren in obvious distress, standing in the middle of the road. Along the side of the road, bomb victims are sitting in a long line, legs folded to their chests. They seem utterly dazed. No one seems to be wailing or crying out. Skin and clothing hang from their arms in tatters. Two of the men appear to be burned bald. They all stare, as if in a trance, at what lies before them in central Hiroshima: a tornado of flame and smoke edging closer to the suburbs.

When Matsushige lined up the second photo in the same spot, he recalls, tears flowed and blurred the viewfinder. "I thought America had done such a terrible thing," he says, "even though they had to win the war."

All of the figures in both photos have their backs to the photographer. They are staring at the approaching holocaust, not at Matsushige. Later that day he would take three more pictures, nearer his home. In none of the five photographs does anyone look at the camera. And not one of his photographs shows a corpse.

Yet the two pictures taken on the Miyuki Bridge capture the horror of the atomic bombing better than any of the photos of lifeless faces and broiled bodies that followed. Perhaps that is because the people in Matsushige's photographs are not feeling the aftereffects of the explosion -- they are experiencing the bomb itself. The atomic bomb has not yet finished with them or their city. In Matsushige's photos the bomb seems to have a life of its own, and it is still advancing.

With their backs to the photographer, we cannot read the victims' expressions. But the terror evident in the way they are moving or simply standing says more about the human response to the monstrous unknown than any horror film or nuclear holocaust drama on television. And because the photographer has the same perspective as his victims, we see what they see. We are on that road to Hiroshima, three hours after the bomb fell, staring into the black whirlwind. Matsushige turned an apparent weakness -- the inability to focus on a single face -- into two of the most unselfconsciously artful photographs ever taken.

The photos are so affecting perhaps because, ever since Aug. 6, 1945, all of us have, in a sense, been standing on the road to Hiroshima, alive but anxious, peering off into the distance at the smoke and firestorm.

Today, Yoshito Matsushige lets antinuclear groups reprint his unique photos without charge. "When I think about the day I took these pictures, I can never think about making a profit off them," he explains.

A frail man with thinning hair, now in his early seventies, Matsushige sits in a chair along a massive table in a conference room on the eighth floor of the new Chugoku Shimbun building, just across from Hiroshima's Peace Park. It seems cruel to ask the question: Does he wish that he had captured 19 additional images on Aug. 6, 1945?

"I'm often asked that," Matsushige says. He looks down at his skinny hands, and rubs his palms together hard. He may be asked this question often, but he doesn't seem to have a pat answer. "Now we see an everlasting arms race," he finally replies, looking up. "Given that situation, you'd think I'd wish I'd taken more. If I had more pictures they could be very useful. Sometimes I think I should have gathered my courage and taken more photos."

He looks down again. "But at other times," he continues, "I feel I did all I could do. I could not endure taking any more pictures that day. It was too heartbreaking."

With that, Matsushige packs up his things, bows deeply, and leaves the room, dapper in a straw hat, blue suit and bright white shoes, carrying under his arm a portfolio of photographs like no other in history.