Short form: a guy is transporting an unloaded handgun into his house from his car and then back out. Off-duty cop from across the street freaks out, charges in, guy with the unloaded gun runs into his own house, cop kicks his door open and shoots him. Guy is fighting for his life right now. The guy who was shot has no criminal record, gun was 100% legal *and* unloaded. Cop is claiming the guy shot pointed it at the cop, witnesses disagree.
This is by far not the first weirdness of this sort coming out of Philly of late. Tom Gresham recently commented that police trainers are having cops shoot in practice on the "go command" of "GUN!".