That's understandable. This was in the southern portion of "North Philly." If you stick to Center City, it's usually OK, or at least it was a half-dozen years ago. I was there visiting a son who was in grad school at U-Penn. He grew to dislike Philly because of incidents like this. But, when I was there, I went to a great museum, patted the Rocky statue, and made sure I was in a usually safe area, since the wife and I are too old to run or fight very well.
Thankfully Valley Forge looks far enough away from the city, that I shouldn’t run into any problems there.