This morning, 3/1/11, in RDU's new terminal, the fire alarms went off. An order was given to evacuate the building. (Some of us left the gate via the emergency exits and gathered on the tarmac). Most everyone stood around the gate; airline personnel blithely ignored the alarms and the announcements, and even resumed boarding flights while the alarm and strobe lights continued to annoy travellers....
Airline folk shooed us back into the terminal and got our flight boarded....

Do we need to see smoke before we observe airport alarm systems?

I raise this because I'm genuinely confused! (Also still recovering from the ringing in my ears from listening to the alarm and strobes for a half hour or so...).

I assume they eventually turned the alarm off and issued an all clear? Is there a story or explanation?