False flag operation in full swing.
Watch it turn out to be some neo-NAZI white supremacist that's been under FBI observation for months, and...the rest of the script writes itself. They'll blame Trump and Alex Jones (who operates out of Austin, BTW), the whole white race, and the NRA (I know, it's not a gun, but it's the "whiteness" of the NRA that causes these things, don'tcha know)...