Back when I was in high school, it was a brand new building, with all the typical flaws of cut-rate, lowest-bidder construcution. Of course, the fire system went off for no reason; alarms lasting anywhere from 2 seconds to 10 minutes. It was such a running joke that when a real emergency came one day (a bomb threat), a few of us got up, but an administrator warned us to ignore the siren, as usual. Well, about 30 seconds later, they warned us this was indeed an emergency...certainly not a laughing matter nowadays.
In any case, I think of those poor people in the second tower WTC who were told to come back to work after the first buliding was hit...an emergency usually happen every day, thus it's something to be taken very seriously.