When English teacher Karen Kriegel heard the news, she couldn't just stay in her downtown office; she had to do something. So she printed up some handmade signs that said GIVE BLOOD NOW, photocopied them at a copy shop and headed for St. Vincent's. As she started walking and handing out flyers, 100 people started walking with her. When they reached the hospital, the gurneys were everywhere, and rolling desk chairs covered with white sheets had been brought out to the pavement to handle bodies. The chairs already looked like ghosts.

Outside the N.Y. Blood Center, the line of prospective donors stretched halfway down the block, around the corner, all the way to 66th Street and around that corner--more than a thousand, all told. Type O donors, the universal donors, were handed little yellow movie tickets and asked to form a separate line. Eventually some blood centers turned everyone else away, told them to come back another day. "It's just amazing," said nurse Anne Taylor, standing in the donors' line. "There'll be a three- or four-hour wait, and just look at all of these people standing here. They can't scare us." Bellevue hospital had so many donors, it ran out of plastic bags.

The warlike mobilization was by no means left to the stricken zones. At Chalkville Elementary School near Birmingham, Ala., more than 700 calls had been received from worried parents, many of whom came at midmorning to pick up their children. Churches and schools and civic groups all around the country offered to help anyone stranded by the grounding of the nation's planes. All over Los Angeles, offices and government buildings were shut down and surrounded by police: city hall, the Federal Building in Westwood, even shopping malls. At the Federal Building, armored rescue vehicles and Ford cars ringed the entrances and exits, with FBI staffers decked out in black and brandishing MP5 assault rifles. Even Express Mail trucks were searched by the FBI before they were allowed onto the premises. Gas pipeline companies were beefing up security at key transmission stations. Grand Coulee Dam in central Washington State was locked down. Gasoline stations around the country were running out of gas as motorists rushed to top off their tanks.

In Chicago, Steve Bernard was huddled around the TV with colleagues on the 36th floor of Chicago's Sears Tower, shortly after 8 a.m., watching the smoke billowing from the World Trade Center after the first attack. When the second plane hit, bewilderment at a faraway spectacle turned into a much more personal, creeping panic. The Chicago staff of the Piper Jaffray investment firm suddenly redirected their gazes toward the windows, quietly searching for jets on their own horizon. The 110-story Sears Tower, even taller than the World Trade Center, is the tallest building in the U.S.; a vulnerable target. Bernard's wife called him and insisted he come home. Within an hour, the building was evacuated.

Across the country, houses of all kinds of worship filled with grieving Americans singing America the Beautiful, wiping away streams of tears. "Humanity came apart in lower Manhattan today, and each of us is wounded. We mourn the loss of our innocence," declared Rabbi Gary Gerson at Oak Park Temple, a Reform Jewish congregation outside Chicago. "Terror has struck us, but it will not destroy us. Now we are all Israelis," he added.

Indeed, there were many Americans who refused to be intimidated by the tragedy, rightly or wrongly. They were reassuring, if not necessarily reasonable. The order to close the U.S. Courthouse in Little Rock, Ark., came shortly before 10 a.m., and it was promptly heeded by everyone except a solitary federal district judge. There sat Henry Woods, age 83, his lined face framed by a mane of white hair, beneath a replica of the seal of the U.S. Around him, at his insistence, a jury and lawyers carried on in a damage suit stemming from, of all things, a 1999 American Airlines crash. "This looks like an intelligent jury to me," Woods said, explaining his refusal to grant a mistrial to the defense after getting word of the disaster. "And I didn't want the judicial system interrupted by a terrorist act, no matter how horrible."

If people all over the country had a sense of being suddenly at war--chat boards on Yahoo filled up with people wanting to volunteer for military service--it was with an enemy they could not see and not easily touch.

Meanwhile the U.S. government reassembled and mobilized. Secretary of State Colin Powell cut short his trip to Latin America to return to the U.S. By midafternoon, members of Congress were calling on their leaders to summon a special session, to show the world the government was up and running. About half of the Senate convened in a conference room at the Capitol Hill Police Station to hear from their leaders--some to vent their outrage at President Bush. Both Democrats and Republicans wanted to know, Where is he? Why isn't he here? Why isn't he in New York? Why isn't he talking to the country? The answer: Bush had been told by the Secret Service, the military and the FBI that it was not yet safe to return to Washington. Only 24 hours later, after absorbing a wave of criticism for his delayed return, did aides claim there had been "credible evidence" that the White House and Air Force One were targets.

Some Republicans on the Hill wanted to know why Counsellor Karen Hughes was the highest government official anyone saw on television all day, other than Bush's brief, unsettling appearance in Louisiana. They wanted to see Bush stride across the South Lawn and show that this is not a country that can be sent into hiding by cowards. "He better have the speech of his life ready tonight," sighed one Republican strategist. Bush did return a few hours later, did stride across the South Lawn and did deliver a reasonably effective national address from the Oval Office. But it wasn't until the following day that he stepped up the intensity of his rhetoric and declared the attacks "acts of war."

Tucked inside the shock and fury was dismay at the performance of others whose job--perhaps impossible--was to prevent this from happening. There were quiet calls for the heads of CIA chief Tenet and FAA boss Jane Garvey for allowing so appalling a breach of security on their watch. And there was an equal determination to find those who were behind it.

Only God knows what kind of heroic acts took place at 25,000 feet as passengers and crews contended with four teams of highly trained enemy terrorists. But it is clear that the hunt for the culprits began way up in the sky, by the doomed passengers and crews themselves, minutes before the attacks took place. In their final goodbyes, on brief and haunting calls from their cell phones, the victims on board at least two of the four planes whispered the number and even some of the seat assignments of the terrorists. A flight attendant on board American Flight 11 called her airline's flight operations center in Dallas on a special airlink line and reported that passengers were being stabbed.

That gave investigators a heads-up that something had gone terribly wrong, but there were plenty of other clues. Even before the smoke had cleared, it was obvious that the culprits knew their way around a Boeing cockpit--and all the security weaknesses in the U.S. civil aviation system. The enemy had chosen the quietest day of the week for the operation, when there would be fewer passengers to subdue; they had boarded westbound transcontinental flights--planes fully loaded with fuel. They were armed with knives and box cutters, had gained access to the cockpits and herded everyone to the back of the plane. Once at the controls, they had turned off at least one of the aircraft's self-identifying beacons, known as transponders, a move that renders the planes somewhat less visible to air traffic controllers. And each aircraft had gone through dramatic but carefully executed course corrections, including a stunning last maneuver by Flight 77. The pilot of that plane came in low from south of the Pentagon, and pulled a 270[degree] turn before slamming into the west wall of the building.

And though everyone wanted to be prudent, there weren't a lot of suspects to round up. Palestinian terror groups are experienced at suicide missions, but have never attempted an operation this large. Groups with links to the Iranian government took down the Khobar Towers in Saudi Arabia in 1996, killing 19, but that target was a long way from the U.S. Libya has lost its taste for terror, most experts believe, and Iraq's Saddam Hussein has always favored loud, brutish force over quiet finesse. Besides, no group other than Osama bin Laden's loose knit network of operatives in dozens of countries worldwide has ever shown the will, wallet or gall to attack the U.S. before. Bin Laden is responsible for the attacks on U.S. embassies in Kenya and Tanzania. Three weeks ago when he told an Arab journalist he would mount an unprecedented attack on the U.S. "This was well funded and well planned," said Senator Pat Roberts, who sits on the Senate Intelligence Committee. "It took a lot of planning. The weather had to be just so on the East Coast. They used sophisticated tactics where they hijacked planes, killed the crew, and they had to have aviators or navigators who knew what they were doing."

Deputy Secretary of State Richard Armitage gathered his senior aides in the State Department's seventh-floor secure facility shortly after 9 a.m. Tuesday for a videoconference with the Administration's top national security aides. National Security Adviser Rice and her top counterterrorism coordinator Richard Clark were on one screen, with FBI Director Mueller and his senior aides, the CIA's counterterrorism director, and FAA officials on others. Vice President Cheney was supposed to be in on the teleconference, but the Secret Service had already spirited him off to a safehouse. "We knew we were in trouble," says one official who was present. "We've got suicide attacks here."

Rice stayed silent as the meeting progressed; Clark did most of the talking. Finally at around 9:45 a.m., aides behind Mueller started murmuring and whispering into his ear. Mueller interrupted everyone. "The Pentagon has been hit by an airplane," the FBI chief announced. All the State Department officials turned their heads to Armitage, who was running the building in Powell's absence. "Let's increase security outside the building," Armitage said calmly, seeming unperturbed. Another aide piped up. "We probably need to think about getting the hell out of here," he said. Armitage decided to evacuate, and an alternate command center was set up at the Foreign Service Institute in Arlington, Va. Senior State Department aides jumped in staff cars to race to Arlington but immediately ran into clogged traffic in Washington.

By Tuesday afternoon, the spooks were making progress. Eavesdroppers at the supersecret National Security Agency had picked up at least two electronic intercepts indicating the terrorists had ties to bin Laden. By nightfall, less than 12 hours after the attacks, U.S. officials told TIME that their sense that he was involved had got closer to what one senior official said was 90%. The next morning, U.S. officials told TIME they have evidence that each of the four terrorist teams had a certified pilot with them; some of these pilots had flown for an airline in Saudi Arabia and received pilot training in the U.S. It's not yet clear whether the pilots were trained in the U.S., or in Saudi Arabia or both. Intelligence officials believe each team had four to six persons. Some team members, it is thought, crossed the Canadian border to get into the U.S. Sources told TIME that within the past few months, the FBI added to the U.S. watch list two men whom the bureau believed to be associated with one of the Islamic Jihad terror groups. Through a screwup, the suspects were lost. The two men appear to have been on the American Airlines Flight 77, the plane that crashed into the Pentagon, sources told TIME. Boston appears to have been a central hub for the operation; U.S. intelligence believes a bin Laden cell in Florida was a support group helping with the aviation aspects of the attack.

Intelligence officials poring over old reports believe they got their first inkling of planning for the attack last June, although at the time the intelligence was too vague to indicate the scale of the operation. In the summer U.S. embassies, particularly those in the Middle East, were put on heightened alert, as was the U.S. military in the region. The CIA was getting vague reports "of some kind of spectacular happenings" by terrorists, said a U.S. intelligence official, but the reports were vague as to timing. "A lot of this reporting we had in the summer that gained our attention and had us concerned, but wasn't specific, could have been tied to this," said a U.S. intelligence official.

Even had they known more, could officials ever have contemplated the scale of this thing? The blasts were so powerful that counterterrorism teams have begun asking the airlines for fuel loads on the plane; aviation experts have been asked to calculate the explosive yield of each blast--in kiloton terms. The reason? Washington wants to see if the planes amounted to weapons of mass destruction. "What we want people to realize is they've crossed a line here," said a U.S. intelligence official. In fact, some senior Administration officials are considering drafting a declaration of war, although the State Department is lery since nobody knows precisely who the war would be against.

By contrast, as the day unfolded, it looked awfully easy to declare war on us. The attack was the perfect mockery of the President's faith in missile defense: What if the missile is an American Airlines plane, and the pilot wants to kill you? It was only eight years ago that a group of zealots led by Ramzi Yousef tried to take the towers down from the bottom, with a rented Ryder truck full of homemade explosives. Their goal, as an unsigned statement presented later at trial put it, was no less than toppling "the towers that constitute the pillars of their civilization."

U.S. officials learned a great deal from that attempt, notes retired ATF investigator Baughn. But the terrorists also learned. "They learned that they had to come at it from a different attitude," Baughn says. "What they've done today was the easiest thing they could do. They didn't have to bring in any explosives. They didn't have to put a group of people together. They didn't have to go find a safe house. They didn't have to go construct anything. They didn't have to rent a truck. They didn't have to load the truck. They didn't have to drive it to some place. All they had to do was hijack an airplane." They made it look so easy, you wondered if the only reason the U.S. has not seen a hijacking in 20 years was because hardly anyone was trying. It's a wonder why not; the Microsoft flight simulator and Fly! II--the two most popular simulators for personal computers--allow you to pretend to fly between the World Trade Center towers, and into them. Anyone looking to practice can buy the software off the shelf.

At 7:30 p.m. Tuesday, with the Pentagon still in flames, the congressional leadership, with a crowd of Senators and Congressmen behind them, stood on the Capitol steps. "When Americans suffer and when people perpetrate acts against this country, we as a Congress and as a government stand united, and stand together," said an angry Dennis Hastert, Speaker of the House, with Democrat Dick Gephardt standing stony silent beside him. Both parties "will stand shoulder to shoulder to fight this evil," Hastert promised. He asked everyone to bow their heads in a moment of silence. Afterward the Congressmen and Senators, Republicans hugging Democrats, broke out into a chorus of God Bless America.

As patriotism swelled, the day threatened to loop us into the kinds of barbaric blood feuds from which we've always been able to stay away. So people lashed out, getting angry at our not very humble foreign policy, complaining about a culture of ironic detachment that made us unmoved by a threat that was very real. (Though in the immediate aftermath of the attacks, pollsters found that by a huge proportion, 80%, Americans were ready to go to war, and prepared for the body bags that go with it.)

Whatever the outcome, it was clear that some things had changed forever. The attacks will become a defining reference point for our culture and imagination, a question of before and after, safe and scarred. By 10:30 Tuesday morning, four tourists from the Czech Republic were at the Empire State building, buying up all the postcards with pictures of the World Trade Center on them. "Soon there will be no more of these cards also," one explained.

When one world ended at 8:45 on Tuesday morning, another was born, one we always trust in but never see, in which normal people become fierce heroes and everyone takes a test for which they haven't studied. As President Bush said in his speech to the nation, we are left with both a terrible sadness and a quiet unyielding anger. He was wrong, though, to talk of the steel of our resolve. Steel, we now know, bends and melts; we need to be made of something stronger than that now--not excluding an unseasoned President new to his job.

Do we now panic, or will we be brave? Once the dump trucks and bulldozers have cleared away the rubble and a thousand funeral Masses have been said, once the streets are swept clean of ash and glass and the stores and monuments and airports reopen, once we have begun to explain this to our children and to ourselves, what will we do? What else but build new cathedrals, and if they are bombed, build some more. Because the faith is in the act of building, not the building itself, and no amount of terror can keep us from scraping the sky.

September 11th and Beyond ~ News and Photos