Yeah, I don't know what else to say about this other than those neighbors are idiots. Not necessarily malicious idiots, but idiots with racial prejudice. Let's just say, if a white man and a white woman were inspecting the house, I doubt they'd have gotten the rifle.
The police... hard to say. Residents of a neighborhood claim strangers are breaking into a house, those strangers can't produce proof they own it (even if they do)... what do you do in that position? Take them down to the station to straighten it out sounds reasonable. Though, if they also didn't also take the rifle-toting yokels with them as well (not sure if they did), that would be something I'd pick on.
Also this. Unless these are like the Georgia Hills and help is 30-45 minutes away (maybe, not a geographic expert), I don't see why anyone would feel the need to take this matter into their own hands.A call to 911 would have sufficed.