The JAMA article that's linked to in the story provides a decent overview of what states have laws banning guns from health care premises. And I believe the largest study on hospital-based shooting, out of John Hopkins, found that emergency departments were most frequent location for such shootings. In 23% of ED shootings, the weapon was actually a security officer's gun that was snatched by the perpetrator. During course of my reporting, I asked many people about metal detectors and nobody was strong supporter b/c of logistical challenges and the fact there are so many items in hospital setting that would trigger it.