I woke up even earlier than usual that morning (my time), and turned on the rather ancient b&w TV I used to have to watch the early morning news. The TV always took a while to warm up and when the picture finally came into focus I saw the shuttle in flight. I wasn't fully awake so I imagine that was one of the reasons my first thought - which I distinctly remember - was something like "A shuttle took off - so what?". Pretty shameful in hindsight, but at that stage shuttle flights had become more or less a routine event. Hardly noteworthy.
Then it exploded.
I basically freaked out, and promptly burst into tears. It was one of my first "where were you?" moments, and remains one of the most horrifying things I've ever seen.