Were I prone to leaving graffiti, under "Fire Extinguisher" I would have written:

Smells Like:
TEEN SPIRIT

That calls for a stick-over label to cover FLASHING LIGHT with THERE IT IS.

I like allanh's comment too.

Actually, growing up in Georgia, tornadoes were common enough that we had to learn the difference between the fire alarm and the tornado alarm. You certainly don't want the school to empty out onto the grounds during a tornado.