9/11 attacks: Images seared in memory

The attacks of Sept. 11, 2001, were carried out in broad daylight, under a clear blue early autumn sky. As such, they were documented in countless photographs and videos. For those who lived through it, 9/11 is etched in memory. But it also will live forever in the incredible images that were generated. Here are a few of the photos that best tell the story of that terrible day.

Before Sept. 11, the notion of using jetliners as weapons was unthinkable.

First one, then the other of the twin towers - iconic symbols of the New York skyline - exploded into smoke and flame. Could this be happening?

When the towers collapsed, pedestrians in Lower Manhattan went into survival mode.

The expression on the President George W. Bush's face said it all.

For many, the shock - and then grief - were simply overwhelming.

The area around Ground Zero became a surreal no-man's land of gray haze and sooty rubble that covered everything and everyone.

The sight of the burning Pentagon - the headquarters of America's military might - was symbolically devastating.

In Pennsylvania, there was another tragedy all its own: the crash of the hijacked United Airlines Flight 93.

Nothing in their past could have prepared New York's firefighters and other first responders for the job they faced after the attacks.

"I can hear you." Faced with the daunting task of rallying the country, President Bush became the man with the megaphone.

Perhaps the most iconic image of all: Amid the tragedy, there was also courage, and resolve.