It caught everyone off guard. And in one second, they knew that this was a day that would forever embed itself in their memories.

On September 11, 2001, terrorists hijacked four planes. The first plane, American Airlines Flight 11, crashed into the World Trade Center’s North Tower at 8:46 a.m. with 81 people on board. More than a thousand people lost their lives in this first attack, and nobody above the 90th floor in the North Tower were believed to have survived.

Some of the people in the building instinctively jumped to their demise to avoid a more painful death from smoke inhalation. According to 9-11 Research, the tower took 102 minutes to completely collapse, allowing most of the occupants below the demolished floor to escape to safety. This was the first part of the attack.

Then, a second plane, American Airlines Flight 175, crashed into the World Trade Center’s South Tower. It slammed into the southwestern face of the building. The impact caused the tower to sway several feet.

Evacuation began after the attack on the North Tower, and since the elevators were still working at that time, most of the South Tower occupants began to move out. Because of a few announcements that assured the tower was safe to re-enter, confusion stormed through. Those who heeded the advice died when the second plane hit and the tower collapsed.

When the airplane hit the South Tower, it cut off several evacuation routes. It left at least one stairwell passable, and some of the occupants in the floors above the crash were able to escape the tower. However, most people were not aware of an escape route, and many people had tried to climb up to the top of the roof in hopes of being rescued there. Unfortunately, the door that led to their freedom was locked, and they were unable to survive.

The South Tower began its collapse about 50 minutes later. At first the top portion of the tower began to tilt southeast. Then, after about two seconds, the top began to fall. After a few more seconds, the top of the World Trade Center’s South Tower was completely swallowed by a dust cloud, and the South Tower was no more. America lost in both trade and in money due to the rebuilding. You could hear the fear of the people inside and outside the towers, and the crying and wailing of the family members of the dead workers inside the towers.

The third plane, an American Airlines Flight 77, crashed into the western part of the Pentagon, and exploded as it smashed into it. The plane demolished mainly new and unoccupied offices. Soon, the western part of the Pentagon, above the impact zone, collapsed. Many Pentagon workers were killed in the crash. Smoke and flames damaged about two million square feet of the military headquarter.

Lastly, a United Airlines Flight 93 plane crashed into a field in Pennsylvania, short of what is thought to be its original target, the Capital.

The catastrophe on September 11, 2001 had a tremendous affect on our country, and it was a devastating day in American history. Not only did it kill thousands of innocent people and destroy critical buildings, it forced America into a war. The attack was an important point in our history and it impacted our nation forever.

To learn more, Infotopia has gathered some student-friendly resources that can be found here.