I was at work, and while other people in the building said they heard a rumble, nothing back in our area. But we had two drops in the Murrah Building, and they both went offline at the same time. No big deal, it happens: a cable pair craps out, somebody cuts a wire, whatever.
Then someone said there was a report on the radio of a explosion downtown. Again, of itself not alarming. A few years before a boiler had blown up at a school.
Then "Turn on the tv!" Did, and saw the mess.
That was not a fun day.