A hijacked jetliner, attacking like a guided missile, tore a gigantic black gash in the building's southwest side, striking with a sickening thud about 9:45 a.m. Smoke and flames billowed from the six-story building throughout the day as firefighters struggled to put out the blaze.
An Alexandria police officer said the jet was going "full power, no flaps," when it struck the Pentagon. Mike Walter, a reporter with USA Today-Live, sat in traffic wondering why a passenger jet was coming so low over a highway embankment.
A moment later, he understood. "I saw a big ball of fire," he said.
Many stood dumbfounded on the highways as the smoke cleared to reveal that at least one of the Pentagon's five rings has been cut clean through, as if by a knife. Some compared the scene to a battlefield: F-16 jets on patrol screeched through the skies and helicopters thumped overhead.
Emergency workers set up hospital tents on the Pentagon lawn, then sent the injured to area hospitals. One employee attended by rescue workers lay on the grass, wearing a neck brace, with heart-monitoring pads on his bare chest.
"The fire was intense. ... We know there are large numbers of injured," Rear Adm. Craig Quigley, a Pentagon spokesman, said at an impromptu news conference at a nearby gas station. "I think what you see here is a full assault on the United States of America."
There was no immediate word on the number of injured. Last night, a grim Defense Secretary Donald H. Rumsfeld told reporters it was too early to have casualty figures.
"It will not be a few," he said. Local hospitals reported caring for 56 Pentagon workers, at least eight of them in intensive care.
Attempting a return to normality, Rumsfeld held his news conference in the Pentagon's briefing room. "The Pentagon's functioning. It will be in business tomorrow," he said.
As of 10 p.m. yesterday, firefighters still battled the blaze, water from hoses arcing toward the orange glow of the fire.
Built during World War II, the Pentagon is the world's largest office building and one of the Washington area's most recognizable sights. It has about 20,000 military and civilian employees. With 17.5 miles of corridors, it can take as long as 10 minutes to get from one office to another in the place known to those who work there as "The Building."
The Pentagon has been the scene of numerous protests, most notably during the Vietnam War, although violence has been rare. On May 19, 1972, a bomb ripped through a restroom, but there were no injuries. The radical group Weather Underground claimed responsibility.
The Pentagon has no defense systems, such as anti-aircraft guns or missiles, that could counter air attacks, said Quigley, who could not recall any suggestion that one be put in place.
Rumsfeld said he was in his third-floor office was on the opposite side of the building when he felt the shock of the explosion. He immediately ran down to the damaged area and helped place the injured on stretchers. "They were bringing bodies out that had been injured, seriously injured," Rumsfeld said.
Then Rumsfeld went into the National Military Command Center, the Pentagon's nerve center, a warren of conference rooms and offices, some equipped with huge display screens for teleconferences among the top military brass. But even in those offices, there was smoke, Quigley said. The damaged Pentagon was placed on "threat condition delta," the highest security condition, he said.
At the time of the attack, Bill Wright, 55, of Washington, a civilian Army employee who works on the first floor, was sitting at his desk and talking with co-workers about the attack on the World Trade Center.
"Something fell out of the ceiling and hit me on the head," he said. The force of the explosion threw him into the hallway 20 feet from his desk.
The doors and walls were gone and everyone seemed to be dusty and bloody. It was eerily quiet, he remembered. Wright lost his glasses and had difficulty finding his way until an Air Force officer helped him from the building, where he saw the burning and twisted metal from the plane.
"I'm just lucky as hell," he said.
Wright told his story on a highway exit ramp. He was still dazed, his head wrapped in a gauze bandage and his rose-colored shirt spotted with blood. Rescue workers cut off his dress pants at the knees to check for injuries.
State police cruisers moved the crowds down the highway shoulders and ordered them off overpasses. Police yelled that another hijacked plane was in the area. "Let's go! Another plane's coming in!" shouted one. Another hollered, "Move back!" But the reports turned out to be untrue and the crowds turned again and stared at the Pentagon's gash and its scorched walls.
Those who worked on the opposite side of the building from where the plane struck reported that the building rocked. One Navy officer said that "the building moved" before a high-pitched buzzer sounded and workers were ordered to evacuate the building.
"Doors flew open," said a trembling Army Sgt. Theresa Stutzman. She used her cellular phone to call her family in Hershey, Pa., and tell them she was all right.
"My parents don't know what part of the building I work in," she said.
Lt. Col. John Bell gazed at the black smoke as it poured from the building. "You just walked out and couldn't comprehend something like this happening so close to home," he said quietly.