Despite their spottiness, the oral histories fill out incomplete chapters in the sprawling chronicle of what happened in New York that morning, much of which took place far beyond the sight of television cameras and their global audience.
Firefighters wondered aloud how they could have attacked a fire reached at the end of a four-hour climb. They marveled at the decency of office workers coming down the stairs, at the bellowing, dust-coated chief on the sidewalk who herded the firefighters clear of the collapse zone, at the voices of experience that brooked no hesitation.
The final moments of the department's senior leaders also rise from the histories as a struggle to rescue dozens of firefighters trapped in the Marriott Hotel after the south tower's collapse. As they worked, the north tower crashed down, killing, among others, Chief of Department Peter Ganci, First Deputy Commissioner William Feehan, and Battalion Chiefs Ray Downey and Lawrence Stack.
Precisely 29 minutes earlier, at 9:59 a.m., the fall of the south tower shook the north tower and stopped the slow, muscular tide of rescuers. By then, the north tower firefighters had been on the move for more than an hour. Each carrying about 100 pounds of gear, only a few had climbed much higher than the 30th floor. Some recalled hearing radio messages from individual firefighters who had made it as far as the 40's.
The calamity next door - the collapse of one of the biggest buildings in the world - was heard but not seen; felt but not understood. The staircases had no windows. Radio communication was erratic. Few firefighters even knew a second plane had struck the other building.
From the street, Chief Ganci twice ordered firefighters to evacuate the north tower, according to Chief Albert Turi, but it was not clear who inside, if anyone, heard him. Even Chief Turi, standing a few feet away, said it had not come over his radio.
Still, many decided to leave after hearing a rumor of a partial collapse some floors above them, or because they assumed another plane had hit.
On the 37th floor, Daniel Sterling, of Engine Company 24, had stopped with firefighters from Ladder 5 and Engine 33 - who did not survive - when the building rattled. A moment later, Firefighter Sterling said, Chief John Paolillo appeared.
"He thought there was a partial collapse of the 65th floor of our building and that we should drop everything and leave," Firefighter Sterling said.
A few floors below, around the 30th or 31st floor, Chief Paolillo was spotted again. "He was yelling, 'Leave your equipment and just get up and go, go, go,' like that," Lt. Brian Becker of Engine 28 said. Chief Paolillo died.
The word to leave was passed to the 27th floor, where many firefighters were resting, including Michael Wernick of Ladder 9. "I know that there was no urgency at that point trying to get out of the building," he said.
"Do you think anyone around you was aware that the other building collapsed?" an interviewer asked.
"No," he replied.
One exception was Firefighter John Drumm with Engine 39, who said that on the 22nd floor, he heard a transmission: "Imminent collapse of the north tower. Immediate evacuation."
'Few Civilians Were Left'
Then he made a point repeated in nearly every interview: "From what I saw on the way down, very, very few civilians were left."
Firefighter Sterling said, "There was nobody in the staircase on the way down."
Lieutenant Becker said, "There were no civilians to speak of in our stairway. There were a couple of stragglers being helped by somebody or other."
Probationary Firefighter Robert Byrne of Engine 24, working his first fire, reached the 37th floor. "I remember going up the stairs took us over the hour," he said. "Getting down the stairs took maybe 10 minutes, not even."
Also on 37, Capt. John Fischer of Ladder 20 discovered that two of his company had gone up ahead. "He was screaming at them for them to get back down," said Lt. Gregg Hansson of Engine 24, who was with Captain Fischer. "Then he went up to get them." Captain Fischer and his men died in the collapse.
Firefighter William Green of Engine 6 was one of the few who said he knew the other tower had fallen. On the 37th floor, "someone opened the door from the 36th floor and said Two World Trade Center just fell down," he said. Over the radio, he heard "Mayday, evacuate."