Yeah, I was at work when Challenger exploded, and didn't even hear about it until that evening, when a waitress at the restaurant where my dad played piano asked if I'd heard about it, and I said yes, because I did know about the launch.
But then she added about what a tragedy it was, and I said "Wait, what? What tragedy?," upon which she told me about the explosion, and I was dumbfounded, and profoundly saddened.
I also remember the explosion of Apollo I, which caught fire during a pre-flight test, and in the pure oxygen atmosphere inside the capsule, the fire killed all three astronauts aboard within minutes. And, many years later, I remember touring the NASA facility at Cape Canaveral, after the name was changed back from Cape Kennedy, and seeing the remains of the capsule, which brought it all back again anew.
I was eight when Apollo I caught fire, and I remember being devastated at the time, as it felt as though we had lost members of our family, the astronauts were all so familiar to us all at the time. And the following days in school, and at home, we were all in mourning, and even more concerned about the remaining astronauts.
RIP to all of the astronauts, Cosmonauts, and others, lost in the pursuit of the dream of manned space flight, all over the world.