What do church, healthcare facility and school shootings in the U.S. have in common?

Only extreme cowards commit such heinous crimes to kill unarmed and largely defenseless, unsuspecting victims!

Between 2008-2018, about 23% of all 277 active shooter events occurred at locations in education, healthcare, and houses of worship (Source). Keep in mind that active shooter is a different definition than mass shootings. The FBI does a lousy job providing this information, e.g. I could not find the full report for this on their website, but I finally found the full 2000-2020 report here. E.g. it is not 100% obvious, whether the active shooter includes criminals primarily shooting at other criminals, I suspect these type of incidents are included, but they should actually be clearly separated: "The FBI defines an “active shooter” as one or more individuals actively engaged in killing or attempting to kill people in a populated area. Implicit in this definition is the shooter’s use of one or more firearms. The “active” aspect of the definition inherently implies the ongoing nature of the incidents, and thus the potential for the response to affect the outcome." I bet, if you subtract those incidents where criminals where primarily shooting at each other, the percentage of active shooter events at locations of schools, healthcare, and houses of worship goes up significantly. Generally speaking, by commingling of criminal and non-criminal active shooters the FBI intentionally inflates the statistics of such incidents! How convenient!

I am afraid schools, healthcare facilities, and churches may have to do more about security and safety.

The excuse or blame of mental disorder is not fully convincing. Have you ever wondered why do psychopaths rarely ever go into e.g. a police station to do their mayhem?