Having been at Ft. McNair, DC, the memory is seared in my mind. I could see the smoke rising from the Pentagon all day. The fort was “closed” and no one was permited to enter or leave it until 5pm. Fortunately the South Capitol Bridge was open by then, thus I was able to get across the Anacostia River and on to home.
My Army civilian job as a historian had me in the Pentagon itself several times a week. I had been in the Army G-1’s office on the previous week on business, thus had met with all of the folks who were killed that day from the airliner’s impact.