I lost seven co-workers that day, none of whom I knew personally, but still an emotional toll. The ones that I knew were on the opposite side of the hit and got out safely. A few days later when I was in the building inventoring my equipment, the odor of jet fuel was still strong.
Had it been a week earlier, many of my co-workers were in that exact space doing an install. Some of the young enlisted had the look of a deer in the headlights afterwards.
In 36 years of military/civilian, it was the only time that I was ordered to leave my duty station because "you and some of the other older will have the ability to get us back in ops in case we are hit."