On this day in history, Islamic extremists following Al-Qaida gained control of four US airplanes and crashed them into the World Trade Center and the Pentagon.The attacks killed around 3,000 people, and another 10,000 were injured.

At 8:45 a.m., American Airlines flight 767 crashed into the 80th floor of the northern Trade Center, killing hundreds and trapping even more on the higher floors. Eighteen minutes later, another plane flew into the southern Trade Center, striking the 60th floor. With debris raining down into the street and the buildings ablaze, America quickly realized it was under attack.

The third plane, another American Airlines flight, circled around the Pentagon before diving into the west side of the military base. A total of 189 people lost their lives in the single attack, and the jet fuel in the airplane set off a devastating inferno around the crash site. America had been struck three times in the past hour, with a fourth attack plane on its way.

However, the final airplane, United Flight 93, knew about the previous attacks due to the nationwide broadcasting of the three previous strikes. The passengers attempted to overpower the extremists, and although successful, every person on the flight lost their life. The intended target of the attack was never revealed, as the plane crashed in a field near Shanksville, Pennsylvania.

Around 10 a.m., the southern Trade Center tower collapsed from the heat of the fires, and the northern tower fell only half an hour later. The falling debris damaged the surrounding buildings, and more than 10,000 people were severely injured. About 400 law enforcement officers and firefighters were killed while helping evacuate the burning buildings and put out the spreading fires.

Since then, 9/11 has since been recognized as Patriot Day, and there are nationwide memorials and commemorations for those that lost their lives in the attacks. Every year on the anniversary of the tragedy, New York City shoots two beams of light from where the World Trade Center towers once stood, and a permanent memorial sits there as well. The memorial consists of two reflecting pools in the shadows of the original towers, with the names of those who died inscribed onto the bronze parapets surrounding the pools.

It’s been 18 years since the 9/11 attacks, but the tragedy has not been forgotten. Its effects can still be felt to this day, from the War on Trade to increased airport security. September 11, 2001 will forever be a part of American history, an event to be remembered not just today, but every day.