September 11, 2001: A clear, crisp fall day in Washington, DC, and New York.

I was shooting a routine photo assignment in the District when my Blackberry went off.

“Explosion: Pentagon” the message read. I walked out on the street and looked towards Virginia. Smoke snaked into the air from the direction of the Pentagon. I loaded my cameras into my Jeep Wrangler and headed towards the 14th Street Bridge.

But police had already closed off the bridge so I headed towards Southeast DC and the entrance to I-295, which led through Anacostia towards the DC Beltway.

While waiting at a stoplight near the main gate of the Washington Navy Yard, I saw Marines armed with M-16s guarding the gate — an unusual site. I snapped some photos from the open Jeep before the light changed.

Arriving at the Pentagon, I pulled the Jeep into the grass alongside Columbia Pike. A morning commuter sat by his car. He looked dazed.

“A plane hit the Pentagon,” he said. “It just flew into the building and disappeared. Then the explosion.”

A light pole crushed the front hood of a taxicab. The driver of the cab said the plane flew so low overhead that it knocked the pole down onto his hood.

I grabbed my cameras and headed a rise to get a better view. Smoke poured out of a gaping hole in the side of the huge structure. An acrid odor assaulted my senses: Burning kerosene and something else — the stench of burning human flesh. I had smelt it before, too many times in on too many occasions. It was something I hoped I would never smell again.

For the next 17 hours, I went on autopilot, shooting photos and handing the compact flash cards from my Nikon D1s to a runner who brought fresh cards and a batteries. I would be several hours before another photographer and I working on that hillside would learn that two other planes had struck the World Trade Center in New York and even longer before hearing the news that United 93 had crashed into a field.

My photos would not only appear on Capitol Hill Blue but in newspapers, magazines and web sites around the world.

And it would be early the next day before I staggered home to our condo in Arlington — only about five miles from the Pentagon.

Stuck in the door was a card from an Criminal Investigations Service agent at the Navy yard. I called the number. He wanted to know why I was taking photos at the main gate the day before.

I explained who I was and gave him the ID number of my Department of Defense press pass. He verified my identity and said he was sorry to have bothered me.

“We have to follow up on these things,” he said. “It’s a bit tense around here.”

Yes, it was. I collapsed into bed knowing that life in America had changed on the day before and would never, ever, be the same.

(The video above was prepared for the first anniversary of 9/11 as my contribution to a local PBS show on the attacks.)