9/11 was a series of coordinated terrorist attacks that took place in the United States on September 11, 2001. The incident claimed the lives of 2,977 people and destroyed the entire World Trade Center (WTC) in New York City including the Twin Towers.
The 9/11 attacks were carried out by nineteen terrorists from al-Qaeda, who hijacked four commercial aeroplanes. After taking control of the aircraft, the terrorists deliberately crashed two of them into the upper floor of the Twin Towers or the North and South towers of the World Trade Center complex.
This caused heavy damage to the Twin Towers, which got engulfed in flames and later collapsed. The North and South towers, which stood at 1,368 feet and 1,362 feet respectively, were the tallest buildings in New York City.
The first two crashes occurred in quick succession with the second plane, Flight 175, colliding with the South Tower 17 minutes after Flight 11 crashed into the North Tower. At the time of the attack, there were roughly 16,400 to 18,000 people inside the WTC complex. While most of the people were safely evacuated from the complex, a total of 2,753 people died in New York that day.
The buildings had burst into flames as a result of the crash and the fire was intensified due to the jet fuel of the aircraft. This caused the steel supporting the building structure to weaken and resulted in the collapse of the towers.
The third hijacked plane was made to crash into the Pentagon in Virginia state of the US where 184 people lost their lives. However, in the fourth hijacked plane, Flight 93, passengers posed stiff resistance to the terrorists after learning about the three plane crashes. Flight 93 eventually crashed into an empty field in western Pennsylvania.
A memorial was built on the 10th anniversary of the 9/11 attacks on the site where the Twin Towers once stood. It hosts two huge reflecting pools with 30-foot waterfalls. The names of the people who died in the attacks in New York have been etched in bronze around the edges of the pool.