9/11 Timeline: How September 11 Attack on WTC, Pentagon, Flight 93 Unfolded

Twenty-two years ago, the United States was the target of the deadliest attack on its soil when 19 men hijacked four airplanes as part of a mission orchestrated by Al-Qaeda leader Osama bin Laden.

Almost 3,000 people lost their lives on September 11, 2001, and more die each year because of related illnesses stemming from the day's events. The attacks on the World Trade Center, the Pentagon and on board United Airlines Flight 93 ushered in a unique period of patriotism as well as a collective recognition that Americans would "never forget" what happened.

With the U.S. now in a period of extreme political turmoil and polarization, the day harks back to a different time of national unity. It may have been short-lived, but it holds a special kind of meaning nationwide and has been taught to generations since.

Over the years, people have honored the lives lost that tragic day in different ways, with in-person ceremonies commemorating the victims and the heroes. Groups even galvanized online during the worst pandemic in a century. The message is that 2,977 lives were not lost in vain.

Timeline of the 9/11 Attacks

4:45 a.m.: United Airlines Flight 93 hijacker Ziad Jarrah, who is at the Days Inn Newark Airport Hotel, starts making phone calls to people in Lebanon and France and a call to his wife, Aysel Senguen, in Germany.

5:01 a.m.: Jarrah calls United Airlines Flight 175 hijacker Marwan al-Shehhi, who is at the Milner Hotel in Boston.

5:33 a.m.: American Airlines Flight 11 hijacker pilot Mohammed Atta and Abdul Aziz al-Omari check out of their hotel room at the Comfort Inn in South Portland, Maine.

5:43 a.m.: Atta and Aziz al-Omari check in for their flight at the US Airways ticket counter at the airport. They check in two pieces of luggage.

5:52 a.m.: United Airlines Flight 175 hijackers Hamza al-Ghamdi and Ahmed al-Ghamdi check out of room 241 at the Days Hotel in Boston.

6:00 a.m.: Atta and Aziz al-Omari board an eight-passenger flight leaving Portland en route to Boston Logan International Airport. While on their way to Boston, national security adviser Condoleezza Rice arrives at her West Wing office and finds "nothing remarkable" in the news clippings, cables and intelligence reports.

6:15 a.m.: American Airlines Flight 77 hijackers Hani Hanjour and Majed Moqed check out of the Budget Host Valencia Motel in Maryland. Hamza and Ahmed al-Ghamdi arrive at the Boston airport.

6:20 a.m.: Al-Shehhi checks out of his room at the Milner Hotel in Boston. At the same time, hijackers Fayez Banihammad and Mohand al-Shehri check out of room 408 at the hotel, and the three drive to the airport.

Hamza and Ahmed al-Ghamdi check in at the United Airlines counter at the airport. They check in two bags.

6:22 a.m.: American Airlines Flight 77 hijacker Nawaf al-Hazmi checks out of room 122 at the Marriott Residence Inn in Virginia.

6:28 a.m.: President George W. Bush is picked up at the Colony Beach and Tennis Resort in Longboat Key, Florida, so he can go for a run. He begins running at 6:40 a.m.

6:45 a.m.: Atta and al-Omari's flight from Portland arrives at the Boston airport. Al-Shehhi arrives at the Boston airport and parks in the Central Parking Garage. Wail al-Shehri, Waleed al-Shehri and Satam al-Suqami, musclemen for American Airlines Flight 11, also arrive at Boston Logan.

6:52 a.m.: Atta receives a phone call from a pay phone inside Terminal C, where United Airlines Flight 175 is boarding, at Boston Logan. It's not known what was said or who was on the other end of the call. It's possible the call was used for tactical communications about the plan or for the hijackers to say goodbye to each other.

6:53 a.m.: Banihammad and Mohand al-Shehri check in at the United Airlines counter. Banihammad checks two bags.

6:54 a.m.: Atta receives a call from a pay phone located between the screening checkpoint and the departure gate in Terminal C at the Boston airport. It's the final call he receives from the airport.

7:00 a.m.: Al-Suqami and Wail al-Shehri and Waleed al-Shehri check in at the American Airlines ticket counter. Al-Suqami checks in one suitcase.

7:03 a.m.: Ahmed al-Nami and Saeed al-Ghamdi check in for United Airlines Flight 93 at New Jersey's Newark Airport. Al-Nami checks in two bags.

7:15 a.m.: American Airlines Flight 77 hijackers Khalid al-Mihdhar and Majed Moqued check in with American Airlines at Dulles International Airport. They're joined by hijackers Hani Hanjour, Nawaf al-Hazmi and Salem al-Hazmi.

7:23 a.m.: Banihammad and Mohand al-Shehri board United Airlines Flight 175. At the same time, Bush's motorcade starts the journey back to the Colony Beach resort.

7:24 a.m.: United Airlines Flight 93 hijacker Ahmed al-Haznawi checks in with United Airlines at the Newark airport. He checks in one bag.

7:27 a.m.: Marwan al-Shehhi and Ahmed al-Ghamdi board United Airlines Flight 175. A minute later, Hamza al-Ghamdi boards the plane, the last hijacker to do so.

7:30 a.m.: Al-Suqami and Wail al-Shehri and Waleed al-Shehri board American Airlines Flight 11 in Boston.

7:40 a.m.: Al-Nami and Saeed al-Ghamdi board United Airlines Flight 93.

7:45 a.m.: Atta and Aziz al-Omari board American Airlines Flight 11. At the same time, Bush skims the morning papers, where the biggest story was that Michael Jordan was coming out of retirement and joining the NBA.

7:48 a.m.: Jarrah boards United Airlines Flight 93 and sits in 1B, the seat closest to the cockpit.

7:50 a.m.: Moqed and al-Mihdhar board American Airlines Flight 77. As they are boarding, Rice receives her intelligence briefing.

7:52 a.m.: Hanjour boards American Airlines Flight 77, also taking the seat closest to the cockpit. He's followed by Nawaf al-Hazmi and Salem al-Hazmi a few minutes later.

7:59 a.m.: American Airlines Flight 11 takes off from Boston with 11 crew members, 76 passengers and five hijackers aboard. It was originally destined for Los Angeles.

8:13 a.m.: American Flight 11 has its last routine communication with Federal Aviation Administration (FAA) Boston Center radio communicators.

8:15 a.m.: United Airlines Flight 175 takes off from Boston with nine crew members, 51 passengers and five hijackers. It was originally destined for Los Angeles. As this hijacked flight is taking off, American Airlines Flight 11 is being taken over by hijackers using knives and threats of a bomb and violence.

8:19 a.m.: Betty Ann Ong, a flight attendant aboard Flight 11, alerts ground personnel that the cockpit is unreachable, a passenger has been stabbed and the plane is being hijacked. The passenger, identified as Daniel Lewin, served four years in the Israeli army and a report speculated he may have tried to stop the hijackers. He's likely the first person killed during the attacks.

8:20 a.m.: American Airlines Flight 77 takes off from Washington Dulles International Airport with six crew members, 53 passengers and five hijackers on board. It was originally destined for Los Angeles.

8:24 a.m.: Flight 11 hijacker Mohamed Atta accidentally broadcasts a message to air traffic control, saying, "We have some planes. Just stay quiet and you will be OK."

8:26 a.m.: Flight 11 makes a hard-left turn to the south, heading toward New York City. Ong reports that the plane is "flying erratically."

8:37 a.m.: Boston's air traffic control center alerts the U.S. Air Force's Northeast Air Defense Sector, which mobilizes the Air National Guard to follow Flight 11.

The FAA also asks United Airlines Flight 175 to look for American Airlines Flight 11, unaware that hijackers are on board the flight.

8:39 a.m.: Bush departs the Colony Beach resort for the Emma E. Booker Elementary School in Sarasota, Florida.

8:42 a.m.: United Airlines Flight 175 is hijacked and has its last radio communication with the ground. Hijackers use the same tactics as those on American Airlines Flight 11 to take control of the plane. United Airlines 93 takes off from Newark Airport with seven crew members, 33 passengers and four hijackers on board. It was originally bound for San Francisco.

8:44 a.m.: American Airlines Flight 11 flight attendant Madeline Amy Sweeney tells Michael Woodward, a Boston flight service manager at the Boston airport, on the phone that she sees water and buildings outside the plane's window as they're making a rapid descent.

She tells him, "We are flying way too low. Oh my God, we are way too low." The call ends with a burst of loud, sustained static.

8:46 a.m.: Flight 11 crashes into floors 93 through 99 of 1 World Trade Center, known as the North Tower, severing all three emergency stairwells. First responders are dispatched to the scene and an evacuation begins.

8:50 a.m.: Bush is told that what's believed to be a small plane hit the World Trade Center. At the time, Bush was visiting the elementary school in Sarasota, Florida, and was told it was likely an accident.

American Airlines Flight 77 transmits its last routine radio communication.

8:51 a.m.: Hijackers begin taking over Flight 77 less than a minute after the message is sent to the FAA's Indianapolis control center that all is normal. Unlike the first two hijackings, there are no reports of the terrorists using threats of a bomb or Mace or any physical violence.

8:52 a.m.: A flight attendant aboard United Airlines Flight 175 reports to an airline operator that a hijacking is underway. Peter Hanson, a passenger, calls his father, Lee, and tells him to call United Airlines and relay the message that the plane has been hijacked. Lee calls the Easton, Connecticut, police department.

8:54 a.m.: Bush arrives at the elementary school in Sarasota.

8:55 a.m.: A Port Authority fire safety employee tells people in 2 World Trade Center, the South Tower, that it is secure and that there is no need to evacuate. Those in the process of evacuating are told to use the reentry doors and elevators to return to their offices.

FAA New York Center declares United Airlines Flight 175 a hijacking and warns it may be heading "right towards the city."

8:59 a.m.: Port Authority Police Department Sergeant Al DeVona orders both towers to be evacuated, followed a minute later by an evacuation order for the entire complex.

Brian David, a former Navy pilot and passenger on United Airlines Flight 175, calls his mother, Louise, and tells her passengers are thinking about storming the cockpit to retake control of the plane.

9:00 a.m.: Bush arrives at Room 301 at the elementary school for a demonstration of the school's early reading program. Peter Hanson, the passenger aboard United Airlines Flight 175, calls his father again and tells him that he thinks "we are going down." He suspects the hijackers intended to go to Chicago or "someplace and fly the plane into a building."

"Don't worry, Dad. If it happens, it'll be very fast," he says before Lee hears a woman screaming and the call ends abruptly.

9:02 a.m.: A Port Authority fire safety employee announces that people can start an orderly evacuation of the South Tower if "conditions warrant on your floor."

9:03 a.m.: United Airlines Flight 175 crashes into floors 77 through 85 of the South Tower. Two of the three emergency stairwells are rendered impassible.

9:05 a.m.: White House chief of staff Andrew Card informs Bush that the South Tower was hit and it was not an accident. "A second plane hit the second tower. America is under attack," Card said to the president.

"My first reaction was outrage. Someone had dared attack America. They were going to pay," Bush later recalled thinking at that moment. "I saw reporters at the back of the room, learning the news on their cellphones and pagers. Instinct kicked in. I knew my reaction would be recorded and beamed throughout the world. The nation would be in shock; the president could not be."

9:12 a.m.: Renee May, a flight attendant aboard American Airlines Flight 77, calls her mother and says the plane has been hijacked. Her mother then calls American Airlines. Minutes after their call, passenger Barbara Olson calls her husband, Solicitor General Theodore Olson, and tells him hijackers took over the flight. He informs federal officials.

9:14 a.m.: Bush leaves the classroom and returns to a holding area in the school. A minute later, he's briefed and watches the television coverage of the World Trade Center attack. He calls Vice President Dick Cheney and consults senior advisers about what he should say to the nation.

9:19 a.m.: United Airlines dispatcher Ed Ballinger begins warning United Airlines Flight 93 and the other 15 flights he's handling to "beware any cockpit intrusion" because two planes had hit the World Trade Center.

9:20 a.m.: FAA Indy Center contacts the Chicago Air Route Traffic Control Center and advises them that American Airlines Flight 77 may have been hijacked. Initially, FAA Indy Center assumed the flight had crashed.

9:23 a.m.: United Airlines Flight 93 receives Ballinger's warning about potential hijackings.

9:28 a.m.: United Airlines Flight 93 is hijacked. During two radio transmissions during the hijacking, the FAA Cleveland Center hears a captain or first officer yelling "Mayday!" and sounds of a physical struggle.

9:30 a.m.: Bush makes his first statement on the attack on the World Trade Center. He calls it a "difficult moment" for America and says it was an "apparent terrorist attack."

9:32 a.m.: Jarrah attempts to make an announcement to passengers, but the FAA Cleveland Center overhears the transmission.

"Ladies and gentlemen: Here the captain, please sit down. Keep remaining sitting. We have a bomb on board. So sit."

9:35 a.m.: A United Airlines Flight 93 flight attendant is heard over the radio saying, "I don't want to die. I don't want to die. I don't want to die."

9:37 a.m.: American Airlines Flight 77 crashes into the Pentagon.

9:39 a.m.: FAA Cleveland Center overhears another one of Jarrah's transmissions, during which he says, "Uh, is the captain. Would like you all to remain seated. There is a bomb on board and are going back to the airport, and to have our demands [unintelligible]. Please remain quiet."

9:40 a.m.: Bush is informed that a plane has hit the Pentagon, and he later recalled thinking that this amounted to a "declaration of war." At the same time, there are reports that the South Tower's collapse is imminent and that additional buildings at the World Trade Center could come down.

9:42 a.m.: The FAA grounds all flights.

9:58 a.m.: United Airlines Flight 93 is flying low enough to the ground that Edward Felt, a passenger, is able to reach an emergency operator in Pennsylvania.

9:59 a.m.: The South Tower collapses.

10:03 a.m.: Passengers and crew members storm the cockpit of United Airlines Flight 93. It crashes in Shanksville, Pennsylvania, about 20 minutes flying time from Washington, D.C.

10:28 a.m.: The North Tower collapses.

12:16 p.m.: U.S. airspace is closed to traffic.

12:18 p.m.: Bush speaks with his wife, Laura. She tells him that she is worried that people will perceive that the government is disengaged. Bush agrees.

12:21 p.m.: Bush speaks with Cheney. The vice president and the Secret Service advise him not to return to Washington because of the confusion and uncertainty.

12:50 p.m.: After much deliberation, the FAA reports that helicopters are "relocating Congress," meaning the congressional leadership. House Speaker Dennis Hastert, third in line to the presidency, is taken to Virginia's Mount Weather Emergency Operations Center.

1:00 p.m.: Bush speaks again with Defense Secretary Donald Rumsfeld, who tells him that he "planned to mount a serious military response."

1:02 p.m.: The FAA reports that, based on bomb threats, towers in Jamaica, New York, and El Segundo, California, are being evacuated.

1:10 p.m.: CIA analysts find two names of known Al-Qaeda members on American Airlines Flight 77's passenger manifest, Khalid al-Mihdhar and Nawaf al-Hazmi. The FBI had reached this conclusion at about 11 a.m.

1:25 p.m.: Bush, still on the ground at Barksdale Air Force Base in Louisiana, talks with New York City Mayor Rudy Giuliani.

1:27 p.m.: The District of Columbia government declares a state of emergency.

1:45 p.m.: Aboard Air Force One, Bush asks his CIA briefer Mike Morell who was responsible for the attacks. Morell says Osama bin Laden.

1:47 p.m.: Ari Fleischer speaks to the press pool aboard Air Force One, saying that Bush had spoken to Cheney "several times," Rumsfeld and "several members of the national security team."

2:23 p.m.: Bush speaks with Cheney and again expresses his frustration that he is not back in Washington. "I don't want whoever did this holding me outside of Washington," Bush says.

2:38 p.m.: Giuliani and New York Governor George Pataki hold a joint news conference at a police academy. Giuliani says that subway and bus service are partially restored in New York City but little service exists south of 14th Street.

2:40 p.m.: Rumsfeld tells his aides that he wants to hit Iraq President Saddam Hussein at the same time as bin Laden. "Sweep it all up. Things related or not," an aide recalled him saying.

2:44 p.m.: Bush, aboard Air Force One, telephones Senator Joe Biden, chairman of the Senate Foreign Relations Committee, but the call cannot be completed.

3:15 p.m.: Bush goes to a small conference room inside the U.S. Strategic Command's Joint Intelligence Center and joins a top-secret video conference with CIA, State Department, Pentagon, Secret Service and FBI officials, among others.

3:36 p.m.: CNN reports scenes of people celebrating the attacks in Palestinian areas of East Jerusalem and the West Bank.

4:31 p.m.: The Associated Press reports that Bush is returning to the White House.

5:20 p.m.: The 47-story Seven World Trade Center building begins to collapse. The building was evacuated earlier in the day and unoccupied. It housed the domestic offices of the CIA and the New York field office of the Secret Service.

5:32 p.m.: Bush, aboard Air Force One, talks over the secure voice line with Laura. "I'm coming home, see you at the White House," he says. He then works with aides on his prime-time address to the nation.

6:00 p.m.: Pennsylvania Governor Tom Ridge says, "It's difficult to describe the range of emotions everyone feels when they not only learn about these incidents today but they've actually seen them."

6:54 p.m.: Bush arrives at the White House and is met by senior staff.

7:45 p.m.: Members of Congress gather on the steps outside of the Capitol and declare that they stand united behind the president. After comments by Hastert and Senate Majority Leader Tom Daschle, they sing "God Bless America."

8:30 p.m.: Bush addresses the nation from the Oval Office, calling the attacks "evil, despicable acts of terror" and saying the U.S. and its allies would "stand together to win the war against terrorism."

11:50 p.m.: Bush and the first lady return to the White House residence.

11:51 p.m.: Bush writes in his diary: "The Pearl Harbor of the 21st century took place today. We think it's Usama [sic] bin Laden."

This timeline was compiled from the 9/11 Memorial and Museum, the country's principal institution for examining the events and aftermath of that day, as well as William Arkin's book On That Day: The Definitive Timeline of 9/11.