People aren't equipped with the words to describe what they saw happenTuesday. So maybe the best way to approximate the horror is to compare it with the movies.

That's what Roberto Duarte did Tuesday, as he talked about watching the collapse of 2 World Trade Center, the tower that up until an hour earlier had housed his office. "It was just like watching

Die Hard

or

Independence Day

," he said.

As someone who saw the collapse, too, I can say, yes, it was.

"It was surreal," Roberto said. He was sitting in the basement of 2 Wall St. with his girlfriend, Kathryn Daniel, waiting for the dust to settle and for some authority upstairs to say it was safe to go outside.

Yes, it was surreal. I agree.

Eventually, the full impact of the day's events will be known -- thedeaths and the injuries, and the toll to be exacted on the survivors. Butuntil people grasp the magnitude of it all, all we can do is tell individual stories until they add up. This is the story of how Roberto and Kathryn ended up in the basement of the Wall Street offices of Banco Portugues Do Atlantico with a collection of total strangers.

Until Tuesday morning, Roberto worked in asset management on the 55th floor of 2 World Trade Center, the southern of the two 110-story towersthat dominated the Wall Street skyline. At about 8:45 a.m., he felt a "shudder." Then, from the trading floor, someone yelled that a plane had hit the other tower. "It was just a stampede for the elevator," he says.

Meanwhile, Kathryn had been at work in her administrative job at 115Broadway, a block from the World Trade Center, in an office facing thecenter. "At first," she says, "I thought the Concorde had done something,because I heard -- it was like a sonic boom." Then, everyone in her officeran to the window to watch the aftereffects of what at first they thoughtwas a bomb. Kathryn worried about Roberto. "I was trying to phone him, and nothing," she says.

Back at Roberto's office, people remembered from years of fire-safetyinstructions that taking the elevator was probably a bad idea, even if thefire was in the other building. So everyone started down the stairs.Somewhere around the 20th floor, an announcement came over the publicaddress system, telling people that 2 World Trade was OK -- that it hadnot been hit.

So Duarte and a colleague, swimming against the tide of people, headedback upstairs -- until they sensibly took the advice of everyone in thestairwell, and continued their descent. "People were saying, 'No, everybodyshould just get out,'" says Duarte. "Which is exactly what we did."

Down at ground level, Duarte looked outside the windows of the building and saw a mess -- paper flying everywhere.

He was down lower, at the building's plaza level, when the second plane hit the tower he'd just evacuated. "I don't know what an earthquake feels like," says Duarte. "But it was like an earthquake. The whole building shook."

"After that," says Roberto, "everybody just started to panic." ButWorld Trade Center staff did a good job, he says, of guiding people to theexits.

Once he got outside, he made his way over to 115 Broadway, whereKathryn and her office mates were in the process of evacuating the building.They met in the lobby, then went outside into the gathering crowdswatching the fires in the upper floors of each tower.

Their own odyssey was over, they thought. But then, at about 10 a.m., 2 World Trade began to topple.

People screamed. People ran. The building wasn't falling toward them,but they were being chased by a huge black cloud of dust that billowed outfrom the World Trade Center.

And what a cloud it was. I saw it from Broadway and Cedar Street. I tried to outrun it as it chased me south down Broadway, but I lost. In seconds it had turned the sky dark, reduced visibility to about a foot, and choked my breath. In an hour, it had deposited a 1-inch thick layer of gray all over Lower Manhattan. New York's own Mount St. Helens.

In their own race for safety, Kathryn fell, ending up with acoaster-sized bruise on her hip. Roberto picked her up. They made it insidebefore the cloud did, then waited with hospitable strangers in a basementlibrary.

Roberto talked a little bit about his job. He said he'd started itafter Labor Day. "Only been there a week," he said. "Some introduction."

But Roberto declined to name the company for which he worked.

And in his refusal lies a lesson about human nature. Amid unspeakable disaster such as what New York endured Tuesday, people keep going, in part, by holding on tightly to whatever part of their once-everyday life that remains. For Roberto, this meant hiding the security badge for his now-nonexistent office and refusing to name his employer. (Taking his lead, Kathryn wouldn't name her company, either.)

Naming his firm, Roberto suggested, could get him into trouble.

Keep in mind that his office at 2 World Trade Center didn't existanymore. He'd watched it crumble.

But Wall Street runs by rules written and unwritten, and one of thepervasive ones is a code of silence. When in doubt, keep your mouth shut.No one ever got into trouble on Wall Street by refusing to answer areporter's question.

And after someone has blown up your building, the rules remain.