I don't know much as far as the legal aspect of it, but I would think it is unethical, and unfair to the staff.
In addition, I think it could backfire pretty big, such as the staff thinking later a real situation was a drill (the whole crying wolf problem) and not taking it seriously. I think it would also really kill your chances of restaffing on following years. I wouldn't want to work at a camp that would do something like that. It could also have legal ramifications, if one of the unknowing staff were, for instance, to call the authorities. Actually, if you want to get really techinical, people could probably sue for emotional trauma. It's illegal to yell fire in a movie theater, because your freedom of speech rights end when you effect others like that, and someone who would yell it would be responsible for anybody who got injured in the stampede out the doors. Likewise, I would assume, the camp director would be responsible for anyone who got hurt in the drill, and that could be applied to mental pain as well.
Besides, that's just messed up. If you can't trust your staff to take something seriously, then there are some major problems there anyway.
