9/11 Timeline: How the September 11 Attacks Unfolded at World Trade Center, Pentagon, Flight 93

Twenty years ago, nineteen men hijacked four airplanes to carry out the deadliest terror attack on U.S. soil in a mission that was orchestrated by al-Qaida leader Osama bin Laden.

For generations of Americans, September 11th became their version of "Where were you when Kennedy was shot?" and millions more can recall memories of that day as if it happened last week. Nearly 3,000 people lost their lives in the attacks at the Pentagon, World Trade Center and aboard Flight 93, and people continue to die every year of 9/11-related illnesses.

While the attacks on September 11th are unforgettable for millions of people, it's an event that others, who weren't alive in 2001, have had to learn about from family members and in classrooms. As is the case with other historical events, education becomes increasingly vital as the years carry on and September 11th is no exception.

The terrorist attacks at the World Trade Center, Pentagon and crashing of Flight 93 killed 2,977 people and injured thousands more. Remembrance events will take different forms this year, as the new coronavirus pandemic continues to limit gatherings, and many people will commemorate the day virtually. Some will read first-hand accounts from survivors and victims or watch news clips and many who were alive for the attacks will remember where they were as the day unfolded.

A Timeline of the Attacks on 9/11

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 one 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 two pieces of luggage.

5:52 a.m.: UA 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 8-passenger flight leaving Portland en route to Boston Logan International Airport. While they're 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.

condoleezza rice 9/11 boston airport hijackers
As former Secretary of State Condoleezza Rice was arriving at her West Wing office on September 11, 2001, two hijackers were boarding a plane for Boston Logan International Airport. (Combo) Rice takes notes from a phone call through a window in the Outer Oval Office, Washington, District of Columbia, September 18, 2001. An aircraft takes off as other aircraft are parked at Logan Airport on January 31, 2019, in Boston, where numerous flights were canceled and delayed due to extreme cold and ice conditions caused by the Polar Vortex over the midwest and northern parts of North America. Smith Collection/GADO/Joseph Prezioso/AFP/Getty Images

6:15 a.m.: American Airlines Flight 77 hijackers Hani Hanour and Majed Moqed check out of the Budget Host Valencia Motel in Maryland. Hamza and Ahmed 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.

We have some planes. Just stay quiet, and you will be okay.

Hamz and Ahmed check in at the United Airlines counter at the airport and check two bags.

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

6:28 a.m.: Bush is picked up at the Colony Beach and Tennis Resort in Longboat Key, Florida, so that he can go for a run. He begins his run 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-Sheri, Waleed al-Shehri and Stam al-Suqami, musclemen for AA Flight 11, also arrive at Boston Logan.

6:52 a.m.: Atta receives a phone call from a pay phone inside Terminal C, where UA Flight 175 is boarding, at Boston Logan. It's unknown what was said or exactly who was on the other end of the call. It's possible the call was used for tactical communications about the plan or to say goodbye to each other.

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

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Undated photos of suspected hijackers of United Airlines flight #93 that crashed in rural Pennsylvania, released by the FBI September 27, 2001, in Washington, D.C. FBI/Getty Images

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, Wail and Waleed check in at the American Airline ticket counter and al-Suqami checks one suitcase.

7:03 a.m.: Al-Nami and Saeed al-Ghamdi check in for UA Flight 93 at the Newark Airport. Al-Nami checks two bags.

7:15 a.m.: AA 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 and Salem al-Hazmi.

7:23 a.m.: Banihammad and Mohand board UA Flight 175. At the same time, Bush's motorcade starts the journey back to the Colony Beach Resort.

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

7:27 a.m.: Marwan and Ahmed board UA Flight 175. A minute later, Hamza boards the plane, the last hijacker to do so.

7:30 a.m.: Waleed, Wail and al-Suqami board AA Flight 11 in Boston.

7:40 a.m.: Al-Nami and Saeed board UA Flight 93.

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

george bush 9/11
On September 11, 2001, former President George W. Bush remembered skimming the newspapers, where the biggest news was that Michael Jordan planned to return to basketball. In this photo illustration by Newsweek, a screenshot of the New York Times shows the day's headline about Michael Jordan. President George W. Bush sits at his desk in the Oval Office of the White House after addressing the nation on the anniversary of the 2001 terrorist attacks September 11, 2006, in Washington, D.C. Roger L. Wollenberg-Pool/Getty Images

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

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

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

7:59 a.m.: AA 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.: AA Flight 11 has its last routine communication with FAA Boston Center radio communicators.

8:15 a.m.: UA 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, AA Flight 11 is being taken over by hijackers using knives and threats of a bomb and violence.

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A Newsweek cover from 2001 shows the attacks on the Twin Towers Newsweek

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 M. 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.: AA 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 okay."

8:26 a.m.: AA 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 UA Flight 175 to look for AA Flight 11, unaware that hijackers are aboard the flight.

8:39 a.m.: Bush departs the Colony Beach Resort for Emma E. Booker Elementary School.

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

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Flight Attendant Madeline Amy Sweeney is seen in this undated photo. Sweeney was on the phone, describing the dangerously low level the plane was flying at before it crashed into the World Trade Center. U.S. Navy/Getty Images

8:44 a.m.: AA 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," and then 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.: President George W. Bush is told what's believed to be a small plane hit the World Trade Center. At the time, Bush was visiting an elementary school in Sarasota, Florida, and was told it was likely an accident.

AA Flight 77 transmits its last routine radio communication.

8:51 a.m.: Hijackers begin taking over AA Flight 77 less than a minute after the message is sent to the FAA Indy 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 UA 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, Florida.

newsweek 9/11 attack new york city
A Newsweek cover from September 2001 shows firefighters lifting an American flag at ground zero. Newsweek

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 there is no need to evacuate. Those in the process of evacuating are told to use the re-entry doors and elevators to return to their office.

FAA New York Center declares UA 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 UA 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, the passenger aboard UA Flight 175, calls his father Lee 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 people may start an orderly evacuation of the South Tower if "conditions warrant on your floor."

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

9/11 timeline of events
Smoke pours from the twin towers of the World Trade Center after they were hit by two hijacked airliners in a terrorist attack September 11, 2001, in New York City. Robert Giroux/Getty

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

"My first reaction was outrage. Someone had dared attack America. They were going to pay," Bush recalled thinking in that moment. "I saw reporters at the back of the room, learning the news on their cell phones 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 A. May, a flight attendant aboard AA 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. He calls Vice President Dick Cheney and consults senior advisers about what remarks he should give.

9/11 george bush dick cheney
(Combo) As Dan Bartlett, Deputy Assistant to the President, points to news footage of the World Trade Center Tuesday, Sept. 11, 2001, President George W. Bush gathers information about the terrorist attack from a classroom at Emma E. Booker Elementary School in Sarasota, Florida. In this handout photo provided by the U.S. National Archives, Vice President Dick Cheney meets in the President's Emergency Operations Center (PEOC) after the terrorist attacks on September 11, 2001, in Washington, D.C. George W. Bush Presidential Library/David Boher/U.S. National Archives/Getty Images

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

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

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

9:28 a.m.: UA Flight 93 is hijacked. During two radio transmissions during the hijacking, the FAA Cleveland Center hears a captain or first officer yelling "Mayday!" and 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 classifies it as 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 UA 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.: AA 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 hit a Pentagon, which he recalls thinking amounted to a "declaration of war." At the same time, there are reports that the South Tower's collapse is imminent and additional buildings at the World Trade Center could come down.

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

9/11 attacks newsweek
A Newsweek commemorative issue from December 2001 reflects on the 9/11 terror attacks. Newsweek

9:58 a.m.: UA Flight 93 is flying low enough to the ground that Edward P. 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 UA 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 closes.

8:30 p.m.: Bush addresses the nation from the White House.

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

This article has been updated with additional information.