Our hospital has a "code violet" which calls in police muscle when patients become violent. It is often an unfortunate escalation as it takes an already scared patient who is mostly reacting in a fight or flight way and turns it up a notch. But I am happy that there are no guns involved...
I try to avoid that whenever possible, however if my nursing staff or the patient are in danger, there is often little choice. I have frequently had to dodge the fist of a octogenarian while trying to calm a delirious patient down before things escalate. It is often the first time the family sees a patient that out of their mind and it is a very scary experience. The patients come out of it, of course, with treatment of their underlying illness but it can takes weeks to months to return to normal (and often will not happen in the hospital or skilled nursing facility because of the difference in their surroundings).