I was in Junior High, just got out of gym class. Was putting on my pants when the principal came on the intercom and gave the school the news.
Spent the rest of the day watching the news in school and the video leading up to the explosion over and over.
I was fresh out of the Air Force, in my first college semester. I had just returned to my dorm after a class, and noticed that the lobby TV had the launch on. Out of probably 3 dozen people in the lobby, only 2 of us bothered to even notice it.
I knew what had happened almost as soon as it hit the screen, though I was incredulous. It took everyone else a little while to catch on, but needless to say it became the topic of the day.