These could be a case for Mulder and Scully. Or your own group of paranormal investigators, monster hunters, innocent people unfortunate enough to live in a World Of Darkness. And so could these.
“Cops Stumble Upon Exorcism” is the episode I most want to see happen.
The Northampton Clown, not so much. I suspect in that case most groups of PCs would shoot first and consider asking questions later.