Before that day, attacks of that nature and magnitude in the United States were considered unthinkable. This photo, shot in Guatemala City, shows the rest of the world as they were forced to take in the events of 9/11 through a television screen. In these images, the emotional toll is evident, as the reality of the death and destruction they are facing is realized by each subject. The two photos above come hours after rescue efforts began, as the firefighters on the scene valiantly attempted a mission that was above and beyond any emergency that could have been imagined at the time. Civilians in the area were forced to flee from dust and debris without the knowledge of what was happening or whether their friends and loved ones were safe. This photo was taken in the aftermath of the collapse of one of the towers of the World Trade Center, as the chaos of the day's events only increased. On that day, 343 firefighters died during their efforts. As they faced death and impossible odds, the Fire Department of New York bravely fought to rescue as many of those trapped as possible. While the rest of the world was watching, some of New York City's bravest men ran toward the flames of the burning towers.

Captured with an American flag in the foreground, this is a fitting symbol of the eyes of all Americans watching the event unfold.

In this photo taken in the period after the South Tower of the World Trade Center was struck and in the final minutes that the two tallest buildings in New York City would stand, smoke is seen billowing out of the buildings. The Inquisitr has also compiled some of the most powerful quotes surrounding the 9/11 tragedy. In memory of those who were lost, below are some of the most tragic photos from the day, as well as some from the events that followed, showing an American psyche that was tested unlike ever before and the true strength exhibited in the wake of such tragedy. As the years go on, a new generation is raised with their knowledge of the attacks confined to a distant memory or a section of a textbook, not completely understanding the true impact of the event and how things changed so quickly in the aftermath. Today marks 18 years since the attacks on September 11, 2001, a day which saw airplanes flown into the World Trade Center and the Pentagon and the course of American history altered forever.

Memory pictures of 911