Killer Clowns Terrorizing People in W.Pa. is nothing new its been going on for years some times a prank gone bad many times nothing more than urban legend. like in Oakmont.

Yes even where I live in the community next to  mine Oakmont Pa. there is an urban legend of a Killer Clown living in the woods of Dark Hollow who will chase and kill you and your remains will never be found.
Of course with a name like Dark hollow do you want to explore the area in the first place.The name possibly comes  from Indian tribes who resided in the area and noted the thick heavy woods and dark areas which see little daylite . However its also a beutiful place to explore with several marked trails.

Nothing more than an urban legend like the wood chopper killer in Pnn hills it probably started by a father to scare his kids so they would not go exploring in the dark hollow  area.By them selves which is never a good idea anyways . The whole Killer Clown thing of late thou  has gotten out of hand. the latest children being chased by individuals dressed in clown masks

http://pittsburgh.cbslocal.com/2017/03/04/armed-men-dressed-as-clowns-scare-children-in-west-mifflin/

In most cases it is just teenagers fooling around trying to scare friends and neighbors and ocassional storys pop up in the news around here over the years .
However criminals have been known to put on clown masks or even dress as clowns to deliberately terrorize individuals or when committing crimes so no one knows who they are .

Of course one of the scariest cases of a real serial killer clown was that of John Wayne Gacy who dressed as a clown for children's party's and is responsible for over a dozen young mens deaths.

https://en.wikipedia.org/wiki/John_Wayne_Gacy

Either way its not funny when your the recipient of some ones prank and some ones liable to get killed by some one they scare who is a legal permit holder . So have fun but do so wisely.
http://www.seattletimes.com/life/whats-up-with-these-creepy-clowns/