Family members leave flowers on the "memorial units" at the Pentagon Memorial after the dedication of the Pentagon Memorial September 11, 2008 in Arlington, Virginia.
Thousands of miles away from the Pentagon, Coronado resident Jill Olen can still vividly remember the day everything changed.
"That's one of the things that sticks in my mind,” Olen said. “It was a Tuesday and it was one of the most beautiful days I had ever seen."
Olen had been with the Department of Defense for about seven or eight years on the day of the terrorist attacks of 9/11. Her work at the Pentagon involved counter terrorism.
When the twin towers were deliberately hit by airplanes, Olen left her office to watch what was happening on television.
Seconds later, the building shook violently as American Airlines flight 77 struck the Pentagon.
"As our ceiling tiles collapsed, there was a huge rumble, people were knocked over things were knocked over,” she recalled.
The plane crashed near Jill's office, seriously damaging it.
She immediately began evacuating her surviving co-workers, knowing many others didn't make it.
"And I am just so thankful that I had not been in there at the time of the impact because had the wings not sheared off, that entire section would have been decimated,” she said.
For the next 16 hours in thick smoke, Olen still has the surgical mask she wore as she helped emergency workers as they tended to the injured.
"It was absolutely tragic, there are stories of people first day on the job or second day on the job, had been in the Navy operations center when it was hit," she said.
Ten years later, Olen is now married to a U.S. Navy captain who also survived the Pentagon attack. She said the experience helped her realize she wanted to experience the positive things in life – like love and family.
However, she’s concerned that ten years after 9/11, the United States isn't any safer.
"Unfortunately, most of what we do as a country is respond to an attack, we don't have that proactive thinking like a terrorist, what's coming next so you notice when the shoe bomber was on the plane you couldn’t bring liquids, you have to take off your shoes, it's always reactive,” Olen said.
In others words, she believes you have to think like terrorists and block their moves before they make them.
"It's tough to do because as Americans we have no concept of that kind of thinking, it's barbaric it's inhumane it's prehistoric," she said.
"It will take a lot of cultural transition to think like a terrorist and try to prevent terrorist attacks."