I forget, does ISIS claim responsibility for all recent mass shootings? Honest question.
From what I can tell, no. That's what authenticates these claims a bit for me.
Also, what has been the consistent pattern for almost every mindless mass killing for the past 15 to 20 years? That these mindless mass killings were caused by Muslims carrying out their Islamic jihad.
There should probably be a presumption that until proven otherwise, this kind of was from an Islamic jihadist.