Gothamist hasn't had the pleasure of bomb scare drills at our office, but Keith at Teleport City tells us that his building's actual procedure when there is a bomb scare is to :

I am, however, a bit disturbed that the security protocol for people inside a building that could potentially explode (my office sits above Barnes & Noble) is to not let people leave that building. Or, you know, alert them in any way. Had I not been bored and prone to getting up and staring out the window, I never would have been aware that there was a bomb squad guy downstairs and that the bock had been taped off. Oh well, let that be a lesson to the workers of the world: you should frequently get up and stare out the window for a spell.