HBO produces documentary to help kids understand 9/11

For students from elementary to high school, the Sept. 11 terrorist attack isn't a memory. It's history. A new HBO documentary that debuts on the event's 18th anniversary treats it that way.

Never forget: A timeline of the events of September 11, 2001

On September 11, 2001, more than 2,600 people perished at the World Trade Center, 125 people died at the Pentagon and 256 people died on four airplanes after terrorists hijacked the planes and turned them into guided missiles.