Good Lord, you're spot on correct. A certain amount of hatred, in conjunction with fear of the unknown, has resulted in exactly the examples you've stated. And there's absolutely no reason to think that history won't repeat itself again, or that what we are witnessing here is somehow unrelated. In pausing to think about it, it gives one an eerie feeling.
Though the thread seems to be more about anti-Jewish sentiment, I think anti-Moslem sentiment combined a domestic attack using firearms is a greater risk to our rights. It would give a real boost to the anti gun forces.