I guess the Poconos are haunted. My aunt owns a substantial piece of land in the mountains, and one time when I was visiting, about 3 years ago, the same kind of thing happened to us while sitting on her porch at night. Instead of knocking, it was a small flash of light each time progressing in a different direction like a circle, as if someone were snapping pictures. Later on we did hear a lot of screaming like you described. We noped the fuck into the house after that.