To many museum and cultural property administrators, the idea of having armed security staff is very disconcerting.   The temptation is to rely on law enforcement response, summoned by a call to a 911 dispatcher.  Unfortunately, the potential damage that can be inflicted by an active shooter is horrendous and this paradigm is already shifting within the campus environment.

It's not a good idea to give a gun to every security guard in every gallery.  The bad guys will always have the element of surprise on their side and the last thing we want is a shoot-out in a crowded gallery. And the effort involved in ongoing training and certifications necessary to maintain an armed force is daunting. Instead, consider contracting one or two active duty law enforcement officers who have the tactical training and skills necessary to form a quick response team capable of responding to a violent situation with a higher level of force.  In most large cities, it can take a long time for law enforcement to respond. Maintaining a small but capable response team on site can be an important element in controlling or ending a violent incident in the incipient stages - well before what would otherwise be possible if we were hunkered down waiting for law enforcement to show up.

See the following article for further evidence of this paradigm shift:

"Universities Rethink Unarmed Police"