How is seller supposed to determine who is insane and who isn't, unless as hool notes below there is some label from somebody. But who? Red flag laws require a court determination, I believe? Otherwise, you may run across equal protection problems or just an arbitrary judgement.

If this incident didn't involve tragedy though, it would be laughable. A crazy person takes a child and a weapon into a megachurch, opens fire, and has fire returned by "security" personnel who are themselves armed in a megachurch, all while people are there ostensibly to worship Jesus. Only in America.