Emily Laychak read from the story of a survivor.

"There were so many people lying on the ground, covering the street. Even among those who were barely walking ... some had burned clothes on, most were naked. There were also those whose eyes had been blown out of their sockets by the bomb blast.

"The rivers running through the city were also filled with corpses; many of them were those who had jumped into the river to escape from the fire, or to cool down their burns, only to drown."

Ms. Laychak was quoting the story of Sachiko Masuoka, a survivor of the atomic bomb dropped over Hiroshima 63 years ago yesterday.

Ms. Masuoka is scheduled to speak at Carnegie Mellon University Sept. 26. Her presentation is one of several events slated for "Remembering Hiroshima, Imagining Peace," which kicked off yesterday at the federal building on Grant Street.

"People have forgotten what occurred at Hiroshima and Nagasaki," said Robin Alexander, the director of international labor affairs for the United Electrical, Radio and Machine Workers of America.

"What we're trying to do is make a strong statement that we remember the devastation, and what we want is a world of peace."

As part of yesterday's program, a "flash mob" of several dozen people -- most wearing all black and carrying black umbrellas -- marched from the federal building to the banks of the Allegheny River near PNC Park.

Once there, they collapsed to the ground, where their outlines were traced to symbolize the shadows of people in Hiroshima that were burned into the ground when the bomb detonated, leading to the quick end of World War II.

"The idea is to show graphically, and make people think about, the black rain that fell in Hiroshima and Nagasaki after the bombings," Ms. Alexander said.

Ms. Laychak, a senior at Carlow University, came up with the idea of merging the flash mob and shadow project into a choreographed event.

"We want to draw attention to peace, and the abolition of not exclusively nuclear warfare, but to war in general," she said.