The scene on the highway was surreal. Certain images continue to flash in my memory like they were taken from a photo album. I can see two men, one jumping from a car and the other from a truck, both pointing frantically at the Pentagon as a dark, black cloud rose above the burning building.

I remember vividly that as I turned off my cell phone I was watching the almost serene image of thick pieces of flaming fiberglass insulation floating down onto the highway.

It all seemed to be happening in slow motion — the scenes were unreal, like something from a movie. I can remember thinking to myself: "I don’t believe this is happening."

But there was no mistaking that I had just witnessed an act of war. The scale of what had happened in New York and just a few kilometers from my office, all in less than an hour, was unfathomable.

Very quickly I realized that I had few choices. Traffic was still jammed and I faced the real prospect of being stuck on a bridge above the Potomac River.

I followed the lead of the driver in front of me and made a U-turn into an on-ramp that was supposed to bring cars onto the highway. Both of us waved our arms to motion those just entering the ramp to turn around.

In less than half an hour I was back in the office watching the television with my colleagues in disbelief as the second of the two towers came crumbling to Earth with thousands of people still inside.

That too seemed unfathomable, but I knew it was real.

Our colleagues at SPACE.com in New York had similar experiences. Some of them were watching from the 35th floor of our headquarters building near Times Square when the second plane hit the World Trade Center. And it dawned on them that midtown Manhattan might be the next target.

Now we all fear that we could be next.