Pop Corn Un-cautiously!
So if you need to shut down any old building temporarily, just bring in some microwave popcorn. Load it into as many microwaves on as many floors as you can. Set the timer to, oh say, something like 3 to 5 times as much time as recommended and leave ASAP.
You know the drill by now!
"Just Set It and Forget It!!" (thank you R.P. for your rotiss-a-thing-a-majig)
City tells workers: Pop corn cautiously - or else