If “we” (the posters here) included all the mass shootings that have occurred in our society, in this country, it would be a long list. And it is perpetrated upon ourselves, as these are people who live in this country and are part of this society and have been all their lives (for the most part, until we get to the more recent “Muslim terrorists” — but that hasn’t slowed down the mass shootings that our own people do on themselves, either...).
I don’t accept “we” for something somebody else does. You might belong to a collective that says it’s “we” that you belong to, but I don’t.
I take responsibility for me, not “we”.