September 11 was a day that changed the world and plunged the United States into a war against terrorism that could last for years. It's a battle that some have compared to the Cold War in its possible duration.
The first strike that would send the country into its war on terrorism occurred in lower Manhattan, on a clear and otherwise uneventful September morning. "We saw a plane coming very low and everyone said, 'Wow, that plane is very, very low'," said an eyewitness. "I was walking to work and all of a sudden I see a jet crash into the first tower."
Authorities first thought it had been a terrible plane crash. But minutes later, it became clear this was no accident, but a deliberate act of terrorism the first of four hijackings that, by day's end, would mark the worst terrorist attack on the United States ever.
President Bush first learned of the attacks during a visit to an elementary school in Florida. It was the much publicized photo of the president, looking stunned as the news was whispered in his ear by his chief of staff, that summed up the shock Americans across the country felt as they learned the nation was under attack.
Within minutes, the military was placed on its highest state of alert. From an Air Force base in Louisiana, Americans saw their president unable at that time to return safely to Washington, attempt to reassure the nation, while not knowing whether the country was still under attack. "Make no mistake, the United States will hunt down and punish those responsible for these cowardly acts," Mr. Bush said. "Our military at home and around the world is on high alert status. The resolve of our great nation is being tested. Make no mistake, we will show the world that we will pass this test."
And then, just minutes after they were hit, both of the 110-story World Trade Center towers collapsed into a billowing cloud of dust and debris. "We've got an explosion inside," said an eyewitness. "The building's exploding right now. People are running up the street. The whole building just exploded."
"It collapsed!" exclaimed another. "The top floor has collapsed down. I saw it blow and then ran like hell."
A thick blanket of soot plunged much of lower Manhattan into near darkness and covered everything for kilometers around. "I tell you, you can't describe it," said another eyewitness. "The TV pictures can't even describe it. It's utter, utter devastation. It's ungodly."
A third hijacked airliner struck the Pentagon. Then, a fourth - believed to be headed for the White House - crashed in rural Pennsylvania after passengers tried to overpower the hijackers.
Despite a series of warnings over the years that the country needed to do more to combat terrorist threats, the nation was caught off guard by terrorists who were able to kill thousands of people in a sudden, unexpected strike. New York Mayor Rudy Giuliani led his city through its darkest hour. "Every effort is being made tonight to try to recover as many people as possible," he said. "It's a horrific site. The numbers are going to be in the thousands."
National Guard units were called out in New York and Washington and the skies over both cities were patrolled by military aircraft. The White House, Pentagon and Congress were evacuated. Manhattan was largely shutdown, the stock market remained closed for days and major sporting events across the country were canceled.
For the first time ever, all commercial flights nationwide were grounded. U.S. ports of entry were sealed and planes destined for the United States from abroad were re-routed to Canada.
By the evening of September 11, the national mood began to change from one of shock and disbelief to questions about why and who would have the desire and skill to stage such an advanced attack. Suspicion immediately focused on Osama bin Laden's al-Qaida network, but it would be some time before the identities of all 19 hijackers, 15 of them from Saudi Arabia were known.
A president only a few months into his term was about to face his greatest challenge: to hunt down a faceless, stateless enemy. Vowing retaliation for mass murder, he outlined the war ahead in an address to a joint session of Congress. "Our war on terror begins with al-Qaida," said the president. "But it does not end there. It will not end until every terrorist group of global reach has been found, stopped and defeated. Americans should not expect one battle, but a lengthy campaign unlike any other we have every seen."
Within less than a month, the war against terrorism had begun in Afghanistan, the ruling Taleban toppled from power a month later. In the time since, Americans have been repeatedly warned that the nation will be attacked again. A year later, the government still has not found al-Qaida leader Osama bin Laden, the accused mastermind of the September 11 attacks, and is uncertain whether he is even dead or alive.
Part of VOA's series on the September 11 terror attacks.