Truck 105 near the west facade of the Pentagon, where Flight 77 hit

The first fire crews to arrive at the pentagon that morning didn’t know where their commanders were. But they didn’t need to. When a building is burning and people are trapped inside, you don’t stand around waiting for orders. Their highest priority was search and rescue. Once that was under way, and more crews had arrived, firefighters would begin “suppression” efforts—hosing down the fire and beating it back.

The crew of Truck 105 out of Arlington, Virginia—Derek Spector, Brian Roache, and Ron Christman—could tell by the people staggering out onto the lawn on the Pentagon’s west side that there were probably still victims trapped inside the building. Military personnel were gathering with backboards to help transport people who couldn’t walk. Defense Secretary Donald Rumsfeld materialized briefly, in his jacket and tie, and helped carry a victim on a stretcher. With so much chaotic activity in the area, few people seemed to notice him.

After pulling on their protective gear and air packs, the firefighters hurried toward the nearest entrance. Spector, the acting commander, reminded them not to run. Walking would give the crew a few crucial seconds to focus on the job ahead. And running would only make them winded and raise their adrenaline levels. They needed to be steady.

Like a lot of firefighters, Spector qualified as a “supertick,” a lifelong fire hound who lives to go on calls. He first joined the fire service as a teenager, in Gaithersburg, Maryland, where the department had been manned by gruff, old-school guys who thought little of getting singed in a fire. The roughneck ethos rubbed off on the stocky, gregarious fireman. But Spector was careful and professional too, a good candidate to be promoted to captain.

As the three entered the building, they saw that both of the massive eight-foot-high oak doors guarding the entrance had been blown off their hinges, seared and splintered. A few burned, blackened victims stumbled past.

Inside it was dark. A handful of officers from the Pentagon’s police force, the Defense Protective Service, were darting in and out of smoky offices, looking for people. In the haze, they were mere shadows. There was muffled shouting.

“I think I hear somebody over here!” came a cry. Somebody else implored, “Check this office. Hurry!”

Spector gathered a few of the Pentagon police officers. “Don’t let anybody else back inside the building,” he urged them. “It’s too dangerous. We’ll be the ones who search for survivors.”

He told his crew to pull on their air masks and start their air. While Roache was adjusting his equipment, an Army officer came running up to him, hollering about somebody on the second floor they needed to rescue. “There’s a general up there,” the man pleaded. “He’s important. You’ve got to get him!”

“We’re doing what we can,” Roache answered. “Now you gotta get out of here.”

The Army officer wouldn’t give up. “He’s important. He’s a general,” the officer kept repeating.

Roache, anxious and wired, lost patience. “As far as I’m concerned, everybody’s important.” he snapped. “We can’t just run in and save the whole building. You’re wearing me down, man. You need to get out of the building.”

“I’m sorry, you’re right,” the soldier glumly acknowledged, beginning to hack from the smoke. He turned and headed quickly for the door.

The three firefighters were standing in the building’s equivalent of a four-way intersection. In front of them was Corridor 5, a spoke leading to the open courtyard at the center of the Pentagon. On their left a hallway, the E Ring, led away from the fire; on their right it ran directly into the impact zone. Then there was the third dimension—the floors above and below, laid out in the same fashion. In the smoke and pandemonium, it wasn’t obvious where they should look first.

Somebody else materialized out of the gloom. “I heard a lady screaming down there,” a security officer choked out, pointing down the E Ring in the direction of the fire. That sealed it—they were already on the first floor, and it made sense to head for the core of the fire, where they were most likely to find people needing help.

They pushed through a set of doors into the E Ring. Black smoke suddenly engulfed them, as dark and murky as if they were at the bottom of the ocean. They had trained in conditions like these, but they’d rarely experienced anything like this in a real fire. Spector reached for the flashlight strapped to his shoulder, held his left arm out, and pointed the beam at the reflective stripes at the end of his sleeve. He could barely see them. Visibility was less than two feet.

The Arlington County Fire Department had recently issued some of its crews thermal imagers—sophisticated and expensive new equipment similar to the night-vision devices military units carry in the field. The devices allow firefighters to see people in conditions with zero visibility by sensing their body heat. Truck 105 had a single imager; Spector had trained with it, but he’d never used it in a live fire.

The imager, shaped like a handheld spotlight, worked like a digital camcorder, except that everything appeared in black, white, and gray. Hot areas were bright white, while cooler areas were darker. The screen showed only thermal representations—but those would be enough to guide Spector and his crew through the smoke.

Spector told Roache to take the left side of the hallway and Christman the right. The two began moving slowly, blindly, down the hallway, using their hands to make out doorways. Spector stayed a few paces behind, in the middle, watching both men through the thermal device, the bright white figures like spirits from a ghost movie.

Instead of the usual flat, predictable contours, the walls were bowed and caved in from the explosion. The firefighters stumbled over debris and had to crawl over obstacles. The undulating walls were the only guideposts they had, so they stuck to them, moving as quickly as they could through the bewildering, new-formed maze.

Standard procedure called for a quick scan of each room with the thermal imager. If no heat from a living body registered after a few seconds, they’d move on. “I’ve got a doorway!” Roache called on the left.

Spector poked his head into the room and used the imager to survey from corner to corner. He saw no sign of life. “Okay, let’s go,” he announced, and they continued down the mangled hallway.

“I’ve got an office here,” Christman bellowed on the right. Spector sidled over and went through the same drill. On the thermal imager there was plenty of heat but none of the telltale white splotches that would indicate a living being.

They checked a few more offices as they struggled down the hallway, breaking through doors that were jammed or locked. They found nobody, which was puzzling. Had everybody gotten out? It seemed unlikely, given the demolished offices they were encountering. Still, the rescuers weren’t finding any victims, dead or alive.

The hallway was getting thicker with debris. Cables and wires, pipes, and pieces of the ceiling dangled from overhead, making it hard to walk upright. To move forward, the firemen had to duckwalk, squatting down on their haunches and waddling beneath the overhanging hazards.

Spector started to hear occasional thumps, like snowballs splattering on asphalt. He pointed the thermal imager upward and could see that bits of the ceiling were melting and falling down around them in globs. Some of the chunks were as big as baseballs, and they were red-hot.

There was something even more alarming in the imager. Spector pointed the scanner straight ahead, and through the tangle of cables and wires saw a glowing heap of debris—it looked like a mountain of garbage that had been doused with gasoline and torched. Although it blazed only about 25 feet away, Roache and Christman were essentially blind in the smoke and couldn’t see it. “Hey guys,” Spector called out. “I’ve got a huge debris pile right in front of us. It’s probably three-quarters of the way to the ceiling.” He paused, wondering what they should do. Should they try to go around it, or go somewhere else?

Christman, the rookie, sounded eager to push on. “Let’s go around it,” he said. Roache didn’t want to turn back either. Having wriggled this far down the E Ring without finding anyone, none of them wanted to give up. The heat was still bearable, and if there were people trapped nearby, they were probably near that pile.

But Spector had a bad feeling. He didn’t know how far the pile went, what was beyond it, or how stable the building around them was. The bits of melting cement falling on their heads were unnerving. “I don’t think we need to be on the other side of that pile,” he told his men. “I don’t want to get someplace we can’t get out of.”

They backed out the way they came, crawling over wreckage and feeling their way, Spector issuing guidance gleaned through the imager. In a few moments they were standing back in Corridor 5. The excursion down the E Ring had probably taken less than 10 minutes. They decided to head further into the building and turn down the D Ring in the same direction, to see whether they could find anybody there.

As they pushed on, Spector tried his radio. “One-oh-five to Command,” he called out. There was no answer, so he repeated the call. Then a shrill tone told him he was out of range, cut off from communications with the outside. That was enough. “Our radios are out,” he told Roache and Christman, gesturing toward the exit. “Let’s go.” They weren’t going to help anyone by getting trapped.

Outside, they removed their face pieces, Nomex hoods, and helmets. The bright sun stung their eyes, but it was a relief to inhale freely and not try to conserve air with every breath.

Spector knew he needed to reach a command officer and report what they’d seen inside, especially the crumbling ceiling. He looked around, searching for a command post. “I wonder who’s in charge around here?” he asked himself out loud. There seemed to be no sense of order or control to the operation yet.

So he tried the radio again. The operations frequency was overwhelmed with traffic. “One-oh-five to Command. Chief,” he said, not knowing which chief he might be talking to, “we’ve been on the inside. The structural integrity of the building is severely compromised. My recommendation is, send nobody inside.”

A medic unit interrupted, calling in a request for all available rescue teams. “Okay,” a voice from the command post crackled back. “Where are you at?” Spector wondered if the voice was talking to the medic unit or to him. In the confusion it was impossible to tell.

Rick Newman is chief business correspondent of U.S. News & World Report. This text is adapted from Firefight: Inside the Battle to Save the Pentagon on 9-11, co-written with firefighter Patrick Creed (© 2008, Creed and Newman), by arrangement with Random House.