At 10 a.m. that day, attack plus one hour, there was an exodus of ashen New Yorkers on the bridges to Brooklyn, girls in suit-pants and heels, and men half-naked in tennis shoes, an orderly flight all in all, but there was fear and awe and silence. I was riding in on a bicycle over the Brooklyn Bridge, against the wave, and cops were saying “Turn back, they might blow the bridge too” — a false rumor, the day was full of them — and F-15 fighter jets pulled long pounding low-altitude arcs over Manhattan. The fallen towers spread soot over the sun, which went out blood-orange and then shone in very blue sky, and the day turned hot. Flurries fell, the sun silvered the flakes: ash on every shoulder and every head, whole ash men; men with bloody eyes bandaged; wet towels over mouths; much thirst, and already the asbestos-filled air making throats hurt and skin heat up, and who knew if there wasn’t something else in the air, anthrax, radioactivity.

When the towers burned in the moments after the collision and before they fell so impossibly and unthinkably, there were people jumping from 70 and 90 stories up, terrified of the fire, which burnt, the firemen say, at 6,000 degrees. A man and woman held hands and leapt. You could watch the heavy ants falling, and many children stood at the windows of schools nearby. Their teachers, too shocked, did not pull them away.

Trucks full of masked volunteers, a dozen ambulances howling, racing south, and in the plaza of the federal courts, scores of men and women frantically nailing plywood planks over long two-by-fours lined parallel 2 feet apart.

“They’ll need a lot more stretchers than this,” a dusty man said walking up. He tells me there are gangs stealing bicycles in Zone 1, busting open Fed Ex trucks, taking advantage of the chaos. Another man saw what was being built. “Oh, God!” he cried and put his hands to his head and leapt backwards.

Rumors of 20,000 dead.

At 7:45 p.m. Tuesday, all power gone from lower Manhattan, 20 blocks of darkness and men running, and the fires stirred winds through the canyons of the buildings, kicking up poisonous dust storms of glass and lime and concrete; 4 inches of ash on cars abandoned with doors open. We wore goggles and facemasks and everyone was in shadow, with flashlights, watching the ground, and the streets looked white as deserts; “the longest night,” the firefighters had said, and we had no idea what they meant or how many they’d lost until the first ruins of the towers rose before us like bombed churches in mist, little red fires at its heart, and we could hear the cries for surgeons among the rubble, someone needed an amputation. And all around were burnt hulks of ambulances, cars, dump trucks, fire trucks — crushed when the towers fell.

“Eyewashes! Eyewashes!” the medics cried out, fanning in teams of two, and the firemen thanked them. And then, into a wall of smoke and out, we entered the very bottom of Ground Zero, and for a moment the medics did not cry “Eyewashes!” This was Hiroshima in miniature: rubble and girders and twisted metal stretching into haze and dust, framed in Roman ruins of delicate charred lattice walls six and 10 stories high, white-pale in arc lights or disappearing in purple plumes — and over the rubble of 200,000 tons of steel and 425,000 cubic yards of concrete and 43,000 windows and 23,000 fluorescent light bulbs, the firemen trawling, stumbling, digging, blasting water, thousands of men among the sharpened steaming warped metal that flipped up underfoot, like bear-traps, tore at legs and popped into chests.

And you knew then that this dig would take weeks, and you’d mention this to a fireman sweating in ash, and he’d say, “Weeks? Fuckin’ months. Fucking forever.”

Within hours, cigarettes taste like burnt plaster and asbestos and sometimes, oddly, human flesh; “real flavor,” someone joked. The hounds and German shepherds are loosed, slipping over the dust on girders, sniffing. You watched the fleet-footed dogs nearly lose their balance over voids 20 feet deep in the rubble; they descended into holes, and then you watched the slimmer of the men do the same thing, hole-crawls with a flashlight and a crowbar.

Volunteer Vinnie Dolan, a young father from Brooklyn, did this again and again, raw and dazed and blank-eyed, spitting green and black phlegm. He brought up three police officers, and at the end of it, the muscles in his cheeks were slackening and tightening involuntarily, his voice was mucusey. At any time the rubble could come down, the smoke kill you in there. A dog came out asphyxiated, and died.

Relief at the smashed-open supermarkets where the meat was already rotting. In these early hours when the volunteers were few, the food supplies random, cops and firemen and EMTs looted cigarettes, candy, water, chips, big boxes of aspirin — terrible headaches that night, it was the asbestos — and Albuterol and inhalers for the asthma attacks. You took what you needed: It was a zone of mud and rubble and men in fatigues and gas masks, and no refrigeration or electricity or running water; you thought to yourself that much of the planet lives like this, and you had no idea what city or country this was. Then you saw cops in the abandoned Starbucks trying to make frappuccinos.

I was given black body bags and Civil Defense body tags and was told to hand them out to the firemen as the dead were brought out, but the bodies were a long time coming. The men dug in groups of two and three, throwing up dust and investment receipts and printer paper and pieces of pipe and wire, and the bucket brigades were just forming. The diggers find flesh; they finger it, hold it up to flashlights; it looks like shredded rope, but “That’s skin,” they say matter-of-factly, then louder, “Think we got a body!” and a dozen men converge. New clues unearthed with hands and shovels: A white knit sweater shredded on tin shrapnel, and a pair of glasses, fully intact — incredible in this mess — and a Nike shoe. “Got a shoe, Chief. Whaddaya think?”

“People get blasted right outta their shoes in shit like this,” replies Chief. “Body could be here. Body could be a hundred feet away.”

A hundred feet where? When the dogs roamed the rubble, they nosed and loitered every three or four feet — everywhere the sick smell of it, parts of bodies, parts of parts, entrails in dust — even the men began to hunt by scent. “I can smell it,” said a fireman, wrinkling his nose. “Right here.” But he found no body. And when the bags went out, they were slumping at the middle, sloshing like water balloons. By the end of the day on Sept. 18, Mayor Rudolph Giuliani announced that only 218 remains had been removed.

A fireman in a Brooklyn bar shook his head at the news. He had done a 24-hour shift. “You have 10-story buildings that leave more debris than these two 100-story towers,” he said. He was awed. “Where the fuck is everything? A serious week-long search and we’ve found 200 in a pile of 5,000? What’s going on? Where is everyone? Why aren’t we finding more bodies? Cause it’s all vaporized — turned to dust. We’re breathing people in that dust.”

Brian McGuire of Rescue 5 from Staten Island told me 300 of his brothers died on Tuesday morning, the worst disaster ever for the firemen of New York City. McGuire hunkered thin-lipped in the bed of a truck tumbled with supplies, the truck was pulling out, fleeing the shadow of a building that was ready to collapse. Vinnie Dolan and I had just been up in that building, ran 20 stories to get the last unwilling residents out; an old woman hunting her parakeet, she wouldn’t leave without the bird.

So I was trembling when I climbed in the truck with McGuire, and he was looking away. “I lost 10 buddies tonight,” he said at last.

There would be firemen marching in the darkness in single file, looking like medieval warriors, carrying awls, pikes, shovels, hoes, and you looked at them differently now, their processions almost holy, because you saw how big their grief was. They’d worked 10 and 20 and 40 hours in the rubble to forget it, to make something good of it, to find a man, a whole man, give him a decent burial, and perhaps find a survivor. You saw them planted in sleep on brown couches pulled from the smashed windows of ground-floor offices, with signs saying “Dave’s Café. Le Menu: 1) water 2) water 3) cold water.” You saw them sitting on curbs, in rows of stunned silence, soot-faced, white-eyed, or on benches in ash-scummed restaurants alone in front of candles, and when you saw them you gave them water. And some wept quietly, then quit it suddenly, like hanging up a phone.

And some, just a very few, were saying evil things, crying vengeance, “Nuke ‘em”; “Kill Allah” written in ash on walls. Stories, seeping in from outside, of jingoist reaction, feral and blind, pig’s blood thrown on mosques, veiled women cursed in supermarkets — war on the Middle East, world war.

There were signs on the inside of madness too: Midday on Sept. 14, a woman arrived screeching, her husband was alive in a void, he had just called on a cellphone from beneath, and the world of the rubble stopped, turned, wrapped itself around her; they dug faster now, doubling their forces. And then it turned out she was a cruel fraud, the story a hoax, and the woman was arrested and was said to be insane.

At the candlelit vigils in the days afterward, there were little cities of lights on the streets. Vinnie Dolan and I watched them in exhaustion.

A candle flared, I nearly jumped; bad nerves. “Can’t sleep,” said Vinnie. “Three hours last night. Hard to sleep.”

The candle had been glued in a Styrofoam cup and the cup had caught fire, hissing. Finally, the candle toppled over in the blaze.