How to evacuate a building without panic - [minor spoilers]

Simply walk in, knock on all the doors, look serious, show some believable ID, say there's been a bad chemical leak and hand everybody a suit. Tell them to put them on immediately and hand over their mobiles because they contain elements that'll set the chemicals off. Escort them out to buses waiting to take them to containment centres. Job done. No panic, no arguments, no sealing of doors, no gas, no field tents, no snipers on roofs... etc.

Any method would be better than theirs, and they'd done it before, so they've had way more time to think of a better solution than the 10 seconds I've just spent.

Anybody think of other ways to evacuate a building without panic?


...it's just another dumb film, get over it.