September 9, 2001, has been embedded into people’s minds, but for all the wrong reasons. Some people have memories attached to it while some can straight away visualize the sequence of the tragedy. Two enormous planes crashing into one of the most recognizable pairs of towers in the country, the scenario was filled with agony. So much so, even after 20 years, people who were involved and witnessed have not been able to get over the trauma that ensued. On the 20th anniversary of the incident, people from all around the world are sharing condolences and warmth on social media. Here are 10 photos from the incident that changed the history of the modern world:

1. September 11, 2001, or as it is more commonly known as the 9/11 attacks, were a series of four coordinated terrorist attacks carried out by the Al Qaeda terror group.

2. The first plane to hit its target was the American Airlines Flight 11. It was flown into the North Tower of the World Trade Center complex in Lower Manhattan.

3. Both 110-storey towers collapsed within an hour and 42 minutes, leading to the collapse of the other World Trade Center structures and damaging surrounding buildings.

4. The third plane, American Airlines Flight 77, crashed into the west side of the Pentagon causing a partial collapse of the building's side.

5. The fourth jet, United Airlines Flight 93 which was flown in the direction of Washington, D.C., was the only one not to hit its intended target, instead of crashing in a field near Shanksville, Pennsylvania.

7. A total of 2,996 people were killed in the attacks, which were the deadliest in human history, with more than 25,000 others injured.

8. It was also the single deadliest incident for firefighters and law enforcement officers in the history of the United States, with 340 and 72 killed, respectively.

9. Following this, then US President W George bush announced a crackdown on global terrorism which led the American troops to Afghanistan and other Islamic countries where Al-Qaeda was operating.

10. Many agonistic photos and videos surfaced after the incident, some of which captured the pain and terror the incident disseminated. One of these pictures of a falling man, who fell from the building after the crash, went viral.