A timeline of 9/11 - what day of the week did Twin Towers attack occur in New York and who were the hijackers?

The date is September 11, 2001, and the world stands still as images of New York's skyline in flames are broadcast across the world. Flights are grounded internationally in fear of a repeat attack after the deadliest terrorist incident in history is unfolding.

Al Qaeda - an extreme Islamist terrorist organisation led by Osama Bin Laden - claims responsibility for four hijacked planes that were deliberately crashed into the World Trade Center, in New York and the Pentagon, in Washington D.C.

The deadly attacks claimed a total of 2,977 lives along with the 19 hijackers. 246 were passengers on board planes, 2,606 were in the Twin Towers, and 125 people were killed at the Pentagon.

On the 22nd anniversary of the tragic event, NationalWorld has compiled a timeline of how events on Tuesday September 11, 2001 unfolded on a day that would change the world forever.

The lead-up to the attacks

5:45 am – A group of hijackers take a flight through Portland, Maine, and land in Boston - passing through security

7:59 am – American Airlines flight 11 takes off from Boston and is planned to head to Los Angeles. A total of five hijackers are on board, along with 76 passengers and 11 crew members.

8:15 am – A further five hijackers are on board United Airlines flight 175 which is also travelling from Boston to Los Angeles with 59 passengers and nine crew.

8:19 am – The first alarm is raised. Crew on flight 11 alert that a hijacking is taking place and passenger Daniel Lewin is stabbed.

8:20 am – American Airlines flight 77 takes off from Washington, DC for Los Angeles. This flight also had five hijackers on board, 53 passengers and six crew.

8:24 am – Air traffic control is accidentally alerted that a hijacking is taking place on flight 77 by one of the hijackers themself

8:37 am – US jets are mobilised from Massachusetts to follow flight 11.

8:42 am – United Airlines flight 93 is delayed but takes still off from Newark for San Francisco. Four hijackers are on board here with 33 passengers and seven crew

The attacks - as they happened

8:46 am – Flight 11 strikes the north tower of the World Trade Center between floors 93 and 99.

8:50 am – President Bush, while in Florida, is first alerted of the incident. At this stage, it was believed that the crash was an accident.

9:00 am – The entire World Trade Center complex is ordered to evacuate while at the same time, a crew member on board flight 175 alerts air traffic control to the hijacking.

9:03 am – The terrorist threat becomes clearer as Flight 175 crashes into the south tower, hitting between floors 77 and 85.

9:05 am – The reality of the situation sets in. A passenger on board Flight 77, Barbara Olson, alerts her husband, US Solicitor General Theodore Olson, to the hijacking with a phone call. He passes on the message to the federal government.

9:30 am – President Bush delivers his famous speech saying saying “terrorism against our nation will not stand”.

9:37 am – Only minutes later, Flight 77 crashes into the side of the Pentagon. All on board are killed along with 125 people in the building.

9:42 am – All US flights are now grounded

9:45 am – The White House and US Capitol are evacuated in fears of another attack

9:59 am – The World Trade Center's south tower collapses, killing more than 800 people.

10:03 am – Flight 93 crashes in a field in Pennsylvania. Passengers on board the fight off the hijackers who were believed to be targeting either the White House or US Capitol.

10:28 am – The north tower collapses, killing more than 1,600 people.

The aftermath

Almost 350 firefighters and paramedics are killed on duty while tackling the fires and rescuing people from the rubble

11:02 am – Former New York Mayor Rudy Giuliani orders the evacuation of Lower Manhattan.

12:30 pm – 14 survivors miraculously escape the rubble of the north tower.

5:20 pm – 7 World Trade Centre collapses, but no one is killed.

Who were the hijackers and where were they from?

Flight 11

Mohamed Atta – Egypt, tactical leader of 9/11 plot and pilot

Abdul Aziz al Omari – Saudi Arabia

Wail al Shehri – Saudi Arabia

Waleed al Shehri – Saudi Arabia

Satam al Suqami – Saudi Arabia

Flight 175

Fayez Banihammad – United Arab Emirates

Ahmed al Ghamdi – Saudi Arabia

Hamza al Ghamdi – Saudi Arabia

Marwan al Shehhi – United Arab Emirates, pilot

Mohand al Shehri – Saudi Arabia

Flight 77

Hani Hanjour – Saudi Arabia, pilot

Nawaf al Hazmi – Saudi Arabia

Salem al Hazmi – Saudi Arabia

Khalid al Mihdhar – Saudi Arabia

Majed Moqed – Saudi Arabia

Saeed al Ghamdi – Saudi Arabia

Ahmad al Haznawi – Saudi Arabia

Ziad Jarrah – Lebanon, pilot

Ahmed al Nami – Saudi Arabia