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

Nineteen 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

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.

8:15 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.

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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.: 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 okay."

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.

8:42 a.m.: United Flight 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.

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.

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

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.

8:52 a.m.: A flight attendant aboard Flight 175 reports to an airline operator that a hijacking is underway.

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.

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.

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.: 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.

9:12 a.m.: Renee A. May, a flight attendant aboard 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.

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

9:42 a.m.: The Federal Aviation Administration grounds all flights.

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

9:58 a.m.: 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 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.