20 years ago the world stood still as the terror of the 9/11 attacks were broadcast around the world.

19 men hijacked four commercial airplanes on the morning of September 11, 2001, and travelled towards major US landmarks in an attack orchestrated by al Qaeda leader Osama bin Laden.

2,977 lives were lost as a result of the attacks which sparked irreversible changes to the world, not least the 20-year war in Afghanistan.

How did the 9/11 attacks unfold? Here is a breakdown of one of the darkest days in US and world history.

A timeline of the 9/11 terrorist attacks

Eastern Daylight Time Zone (EDT)

7:59am

American Airlines Flight 11, a Boeing 767 aircraft carrying 81 passengers and 11 crew members departs from Logan International Airport in Boston bound for Los Angeles. Five hijackers are on board.

8:14am

United Airlines Flight 175, a Boeing 767 with 56 passengers and nine crew members departs from Logan International Airport in Boston bound for Los Angeles. Five hijackers are on board.

8:14am

As Flight 175 takes off, Flight 11 is hijacked over central Massachusetts.

8:20am

American Airlines Flight 77, a Boeing 757 carrying 58 passengers and six members of staff, takes off from Washington Dulles International Airport heading towards Los Angeles. Five hijackers are on board.

8:42am

United Airlines Flight 93, also a Boeing 757 with 37 passengers and seven crew members departs from Newark International Airport bound for San Francisco. Four hijackers are on board.

8:42am – 8:46am

Flight 175 is hijacked.

8:46am

Flight 11 crashes into the north face of the North Tower (1WTC) OF THE World Trade Center between the 93rd and the 99th floors.

8:50am – 8:54am

Flight 77 is hijacked.

9:03am

Flight 175 crashes into the south face of the South Tower (2WTC) OF The World Trade Center between the 77th and 85th floors.

Businessiq: Flight 175 crashes into the south face of the South Tower. Credit: LIBRARY OF CONGRESS/COURTESY OF NETFLIXFlight 175 crashes into the south face of the South Tower. Credit: LIBRARY OF CONGRESS/COURTESY OF NETFLIX

9.28am 

Flight 93 is hijacked.

9.37am 

Flight 77 crashes into the western side of the Pentagon starting a fire.

9.45am

All of United States airspace is shut down with all aircraft ordered to land at the nearest airport.

Businessiq: All of United States airspace is shut down. (Netflix)All of United States airspace is shut down. (Netflix)

9.59am

The South Tower, the second to get hit, collapses 56 minutes after Fight 175 crashed into it.

10.03am

Flight 93 crashes into a field near Shanksville, Pennsylvania. Reports suggest passengers resisted the terrorists after learning of earlier attacks at the World Trade Center and the Pentagon. The 9/11 Commission believes the target was either the United States Capitol building or the White House in Washington.

10.28am

The North Tower collapses one hour and 42 minutes after being hit by Flight 11. The collapse destroys The Marriott Hotel at the base of the tower.

10.50am

Seven stories of the Pentagon collapse amid fire damage.

5.20pm

7 World Trade Center (7 WTC) collapses after substantial structural damage as a result of the North Tower’s collapse.