9/11: Seconds After

On September 11, 2001, America was attacked by the Islamist extremist group al-Qaeda, resulting in a coordinated series of terrorist attacks using hijacked commercial airplanes.
Here's a breakdown of what happened:
The Attacks:
Four planes were hijacked shortly after taking off from three East Coast airports.
Two planes were flown into the Twin Towers of the World Trade Center in New York City, causing them to catch fire and subsequently collapse.
A third plane crashed into the Pentagon, the he...