NEW YORK — Close your eyes and picture Sept. 11. The memories are cauterized, familiar forever. The second plane banks and slides in, the fireball blooms, the towers peel away as if unzipped from the top.
Start with the Tuesday morning and the blue sky and walk through the day from two perspectives, inside and out. From that of a man who managed to survive above the impact zone in the south tower and from that of the helpless, watching world.
In those first two hours, before anyone could put together the full, awful picture, chaos filled in the gaps.
No one knew exactly what was happening, or how vast, or at whose hand. No one knew, for a time, that the instruments of destruction were not prop planes but jumbo jets. At the very first, almost no one knew there were planes at all.
Brian Clark was working at Euro Brokers, on the 84th floor of the south tower of the World Trade Center. He arrived at about 7:15 a.m., had his cup of coffee, went about the morning's chores.
A "loud double boom" is the first thing he remembers. Then flickering of the lights in his office. Something caught his peripheral vision. He spun around. His view usually looked out over the Hudson River. The river and the sky.
"It was filled with flame," he says. "Two yards from my nose is the window, and it's right against the glass, almost swirling. I can't recall whether there was a flash of heat. But the bright glass — you were in the fire. The flames washed right up."
It was 8:46 a.m.
For reference, Clark sometimes tells people to imagine a three-by-three grid, like the first nine digits on a telephone keypad. The north tower sat where 1 would be, the south tower at 8.
Clark's office faced west, near the southwest corner of the 8 button. American Airlines Flight 11 had crashed into the north face of the north tower, the top of the 1 button.
Since the 1993 bombing of the trade center's underground garage, Clark had volunteered as a fire marshal for his floor. Now, as if on autopilot, he grabbed the flashlight, grabbed the whistle.
He remembers encouraging his colleagues to leave the floor. He also remembers one of them, a woman, spinning around from the window in shock and tears, and telling him that people were jumping.
Clark called his wife. "Something's happened next door," he says he told her, "but we're OK."
Just then, the network television morning shows, where the top stories of the day had included whether Michael Jordan might make a comeback in the NBA, cut for the first time to a live shot of the gashed north tower of the World Trade Center.
The first alert on the national news wire of The Associated Press moved at 33 seconds past 8:53 a.m.:
NEW YORK (AP) — Plane crashes into World Trade Center, according to television reports.
At about 8:55, Clark remembers a voice over the PA system: "Building Two is secure."
Eight minutes later, at 9:03, he was standing outside his office and talking with a coworker, Bobby Coll. They were 2 feet to a yard apart, he thinks, eye to eye.
In an instant, "the room exploded."
The feeling was of tremendous air compression. Then things so secure no one ever gave them a thought, things like the lights and the floor, came loose. For several harrowing, torqueing seconds, it seemed the building itself might go over. The power went out.
"Everything was full of construction dust," Clark says. "Yellow, chalky, gritty air. As if you gave a demolition crew a week to destroy the floor, but it happened in a second. It was like someone had torn open a cement bag and just waved it in the air."
He remembers terrorism crossing his mind. He also thought something that seems ridiculous to him in hindsight. He remembers cursing and saying, "We've got to come back tomorrow and clean up this mess."
To the outside world, at 9:04, went the AP alert: "Explosion rocks second World Trade Center tower."
TV networks were in the middle of interviewing eyewitnesses to the first explosion when United Flight 175 approached, slipped into the south face of the south tower, and sent a mushrooming fireball out the other side.
"That looks like a second plane," Charles Gibson said on ABC.
"And now," Matt Lauer said on NBC's "Today" show, "you have to move from talk about a possible accident to talk about something deliberate that has happened here."
With people around the world now fixed on live pictures of the trade center, the puzzle was slowly coming into focus. The AP reported at 9:12: "FBI investigating reports of plane hijacking before World Trade Center crashes."
In Sarasota, Fla., President George W. Bush was reading to schoolchildren when Andrew Card, the White House chief of staff, whispered news of the second crash into his ear. The color appeared to drain from Bush's face.
Inside the south tower, Clark was trying to lead a small, snaking line of people toward a central stairway and down from the 84th floor. Three floors into the trip, they were met by a woman, heading up.
"We've got to go higher," the woman said.
A debate ensued. Up or down. Clark shone his flashlight on whoever was talking. In the middle of the discussion, Clark heard a muffled scream for help coming from the 81st floor. He and a coworker, Ron DiFrancesco, went to investigate.
They squeezed through a crack between drywall and door frame.
"I have this very clear vision of all my coworkers turning around and starting up the stairs," Clark says. "And they all died."
Mid-rescue on the 81st floor, DiFrancesco was overcome by smoke, coughed and sputtered and turned back. Clark continued toward the stranger's voice. It was Stanley Praimnath, an executive with Fuji Bank.
To get to safety, Praimnath had to scale a toppled inside wall. Clark pulled him over on the second try. Clark fell on his back. They introduced themselves and told each other that they would be brothers for life.
They made it down to the 31st floor and called their wives to report that they were OK. It was just after 9:30 a.m. To the outside world, it was about to become clear that the disaster, whatever it was, was not limited to two skyscrapers in New York.
"Today we've had a national tragedy," the president told reporters and young children at the Florida elementary school. " Two airplanes have crashed into the World Trade Center in an apparent terrorist attack on our country."
ABC showed pictures of smoke rising in the distance behind the Old Executive Office Building in Washington, southwest of the White House. A bewildered correspondent said she could not explain it.
"Want to hold our breath here, it just seems to me for a second," said Peter Jennings, the anchor, "and, and, and — and, and not get into a mode that the country is under attack."
At seven seconds past 9:43, another alert on the AP wire: "An aircraft has crashed into the Pentagon, witnesses say." It was American Flight 77. Seconds later, another alert said that the White House had been evacuated.
When Clark and Praimnath finally made it out of the south tower, they looked out at a moonscape. A plaza between the twin towers, normally brimming with life — a fountain, flowers — was abandoned and gray.
As they started toward Liberty Street, the southern boundary, and out of the trade center complex, a fireman told them to run for it. They saw no debris or falling bodies, and ran for it.
They made it into a deli, where, in one of the day's absurdist touches, a worker handed Clark a platter of sweet rolls and melons, wrapped in cellophane. "Take this," he said. "Nobody's coming for this today."
They wound up at Trinity Church, two blocks downtown. They stood gripping the iron railing around the cemetery, close to what they later learned was the burial site of Alexander Hamilton.
They argued about whether the south tower, burning high above, might collapse. Praimnath thought it would. "No way," Clark said. At 9:59, for no specific reason that Clark can remember, they turned and looked up.
It was, Clark says, as if they had been invited to witness the destruction.
"Floor by floor, it kind of dissolved in front of us," he says. "The white wave."
The south tower came down as if something were pulling on it from the top at a hundred different places. It left a column of gray smoke and sent a ghastly plume shooting through the streets of lower Manhattan.
The AP reported it first as a new explosion, then, having confirmed that the building was simply no longer there, moved the news as a flash, the highest priority: "One World Trade Center tower collapses."
Clark and Praimnath dived into a building on Broadway. Clark was still carrying the breakfast tray. He set it on a reception desk and two dozen people, taking refuge in the building, descended on it.
They stayed in the building for perhaps 45 minutes. Praimnath gave Clark a business card. Later, when they left and walked through lower Manhattan, stepping through ash as though it were new snow, they got separated.
Later, the card was only way Clark knew for sure that Praimnath was real, that it wasn't all some fantastic dream.
In the relative safety of the building's lobby, with the storm of ash swirling outside, they missed what happened next.
At 10:29 a.m., a second flash on the AP wire: "Second World Trade Center tower collapses."
Eight minutes later: "Large plane crashes in western Pennsylvania, officials at Somerset County Airport confirm."
The official times were 10:03, for the crash of United Flight 93 near Shanksville, Pa., and 10:28 a.m., for the collapse of the north tower of the World Trade Center.
In all, it had taken under two hours and almost 3,000 souls. The official count of the dead, adjusted slightly every so often in the years after the attack, including for some deaths from respiratory disease liked to the towers, was 2,977.
The count was 40 in Pennsylvania, 184 at the Pentagon and 2,753 at the World Trade Center.
Clark, who lived then and lives today in Mahwah, N.J., got off the island of Manhattan by ferry. He walked east and found that ferries to Jersey City, which usually leave from the west, along the Hudson River, had been diverted to the East River.
He remembers chugging through the dust of Sept. 11, around the base of Manhattan. He remembers "yammering" on the boat — all these people, trying to make sense of what had happened.
Only when the boat got to the Jersey side did Clark realize that both towers had collapsed.
"We come out of the fog, and now the trade center site is visible," he remembers. "And it's blue sky, and they're gone."
© Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.