A Posted Sign That Will Prevent Gun Violence In Schools

You decide.  (Hat tip:  El Opinador Compulsivo)

Actually, I think the sign on the right might prove too frightening to many. I would be satisfied by a sign that merely says "These premises guarded by armed and trained personnel."  Or even "These premises guarded by professional security" with an image of a uniformed guard.  No depiction of a firearm would be necessary -- it would be implied by the image.

UPDATE:  I photoshopped another alternative, less scary but possibly just as effective: