Timeline of key events on 9/11

As the world marks the seventh anniversary of the attack on the twin towers, we look back at the key events of that day .

7.58 - United Airlines Flight 175 to Los Angeles leaves Boston's Logan Airport with 65 people on board, including five suspected hijackers.

8.01 - United Airlines Flight 93 to San Francisco leaves Newark Airport in New Jersey with 45 people on board, including four suspected hijackers.

8.02 - American Airlines Flight 11 to Los Angeles leaves Boston's Logan Airport with 92 people and five suspected hijackers on board.

8. 10 - American Airlines Flight 77 to Los Angeles leaves Washington DC's Dulles Airport with 64 people on board, including five suspected hijackers.

8.28 - An air traffic controller hears one of the hijackers speaking from the cockpit of Flight 11, saying: "Don't do anything foolish. You are not going to get hurt. We have other planes."

l 8.43 - Two F-15 fighters take off after authorities confirm that Flight 175 has also been hijacked.

l 8.46 - Flight 11 crashes into the north tower of the World Trade Center.

9.03 - Flight 175 crashes into the south tower of the World Trade Center.

9.10 - President George Bush is told of the attacks. He had been reading to children in a classroom.

9.29 - Eyewitnesses report seeing people jumping from the Twin Towers.

9.40 - Flight 77 crashes into the Pentagon in Washington DC, causing the collapse of a five-storey section of the building and killing 190 people inside.

9.58 - A passenger from Flight 93 makes an emergency call saying: "We are being hijacked!"

10.03 - Flight 93 crashes 80 miles south east of Pittsburgh, Pennsylvania. Its intended target was believed to be Washington.

10.05 - The south tower collapses, 62 minutes after being hit.

10.29 - The north tower collapses. The death toll was feared to be as high as 20,000 but gradually dropped to about 2,800.