I stayed at my cubicle glued to the radio until about noon or so when they broke off the radio and turned control over to the news. Someone managed to get Internet footage of the collapse which shocked us. I had to pee so bad by that time.
They began evacuating downtown Columbus around one or two. Folks with kids were free to leave. I stayed until about 4pm or so then drove home on mostly deserted roads. The footage on the news was shocking to say the least. I called my parents later in the evening. We discussed parallels with Pearl Harbor (something that I was knowledgeable with).
It is now the five year anniversary of the 9/11 tragedy. People will discuss the politics surrounding this day so I won't. It is a scary fact of life that even though the majority of the people on this planet are good people (stupid and annoying, but good) all it takes is the one in the millions with the right tools, components and drive to destroy a building, city or life as we know it.