When a hijacked plane hits the North Tower of the World Trade Center, the first firefighters on the scene race against time to rescue trapped civilians.

Many workers in the South Tower of the World Trade Center make their way down to the streets, where paramedics face an onslaught of badly injured people.

A hijacked plane crashes into The Pentagon in Arlington County, Virginia. Elsewhere, a fourth hijacked plane crashes in Stonycreek Township, Pennsylvania.

Survivors become separated when they are enveloped by a toxic dust cloud.

A group of firefighters were inside the North Tower when it collapsed, but miraculously survived. It's a race against time to find and rescue them.

It's late in the afternoon, and one side of 7 World Trade Center is engulfed in flames. At Ground Zero, two ex-Marines and an ex-paramedic join forces to search for survivors and pull off one of the most miraculous rescues of the day.