The World Trade Center, in Lower Manhattan, New York City, was destroyed after a series of terrorist attacks on September 11, 2001, killing almost 3,000 people at the site. Two commercial airliners hijacked by al-Qaeda members were deliberately flown into the complex's Twin Towers, at the time among the five tallest buildings in the world. The plane impacts dealt significant structural damage to the skyscrapers and started large fires in the towers, eventually resulting in both undergoing a total progressive collapse.