As they trudged through the smoky darkness in the Pentagon's C Ring shortly before 4 a.m. Friday, Fairfax County firefighters Carlton Burkhammer and Brian Moravitz scanned the debris with their helmet lights, still hopeful of finding someone alive. Moments after spotting a chair from the cockpit of American Airlines Flight 77, their beams flashed on two charred black boxes.

Burkhammer and Moravitz glanced at each other through steamy plastic face shields and respirators. "Is that what we think it is?" Burkhammer asked.

They radioed for federal investigators, who confirmed the discovery of the plane's voice and data recorder systems -- the "black boxes."

It was a singular moment of exultation in a week of otherwise grueling, frustrating work for rescuers from Fairfax and Montgomery counties, who returned home yesterday. Though the teams had experience picking through the rubble of catastrophes, the past week had the additional harrowing aspects of searching while a fire still burned and with the prospect of further attacks.

Both teams arrived on the scene within hours of the attack. After initially helping evacuate the Pentagon, their despondence grew as they found no one else alive. When they delved closer to the heart of the burning wreckage the first day, Fairfax firefighter Thomas Griffin said, "you knew there was very little chance of survivors. That's pretty much when my heart sank."

Fears of further attacks also played in the rescuers' heads. "I think everybody was thinking, 'How much more stuff's going to happen?' " Griffin said.

In Fairfax and Rockville yesterday, cheering, flag-waving family members, friends and encouraging citizens welcomed their convoys of rescuers home. Officials made speeches, and then the family reunions began, with stories spilling out of the terrible week now gone.

For Montgomery County District Fire Chief Richard R. Bowers, the week's defining moment took place not inside the wreckage but on the roof, where firefighters battled continuously to put out the fire.

Bowers said he wanted to store the mental images of about 33 firefighters who worked so hard in conditions so hot they fell down. One man sank to his knees in exhaustion, only to struggle upward again when someone called, "I need you to keep chopping." In the smoke and haze, Bowers saw the man pick up his ax and start swinging again.

About 12:35 p.m. Wednesday, more than 24 hours after the terrorist attack, the question was repeated down the line. "See any smoke?" The answer came back, again and again, "No." Then silence. The fire on the roof was extinguished. With little conversation, the firefighters left to see what else needed doing.

Montgomery firefighter Jeff Stahley, 29, recalled when, about two days after the attack, he realized that his team had gone from what is euphemistically called "rescue to recovery mode."

Training hadn't prepared him for this: finding bodies at such frequent intervals, by the metal of the jet, near desks so crushed they were almost unrecognizable, amid the crumbled drywall and concrete of what had once been humming offices.

"There were bodies everywhere," he said, his face twitching. "People died running for their lives -- that was what was so horrible, that you could see they had died that way."

It was the moment that he gave up hope of finding anyone alive and started hoping to find remains, a stray purse or an identification badge -- anything that could give a family some answers.

The Fairfax team, one of two U.S. squads trained and ready for dispatch anywhere in the world, has extensive experience rushing to catastrophes and attacking huge mounds of twisted steel and concrete. They were circumspect about the carnage they witnessed there, because "families don't need to hear that," Burkhammer said.

Though many of the Fairfax rescuers at the Pentagon had been to bombings of U.S. buildings in Oklahoma City and Nairobi, finding survivors this time took on a special urgency, they said: This catastrophe was in their back yard.

The task force members began packing their gear after the World Trade Center attacks and shifted into high gear when the Pentagon was hit. Several Fairfax firefighters spoke of being awed by how much worse the damage appeared up close than when they saw it on television. "What you could see from the outside is nothing compared to what you see inside," firefighter Charlie Allen said. "The whole inside is gutted. Whole floors wiped out, everything gone."

Burkhammer and Moravitz said they worked their way through burned-out offices, some fairly intact, some devastated. They found a number of desktop computers, then noticed the slightly different-size voice and data recorders. They had been told the recorders would be in fluorescent-orange steel boxes. But the fire had turned them black. One was torn open on one end, Burkhammer said.

"I was delighted," Burkhammer said of finding the boxes, "because we hadn't found any live victims. That's our real priority."

Federal investigators said they had not recovered anything from the voice recorder. Burkhammer said the firefighters were told the data recorder showed that the plane was traveling at 345 mph when it hit the Pentagon.

Dan Bickham, of the Fairfax County rescue team, gets an enthusiastic welcome home from grandson JJ. It was members of the Fairfax squad -- Carlton Burkhammer and Brian Moravitz -- who uncovered the two black boxes.Fairfax rescuer Craig Luecke encircles wife, Jaeanna, son, Jon, 11, and daughter, Jessica, 9, at reunion.Masked rescuers from Montgomery County help clear debris and shore up the Pentagon on Thursday.