??? Of course it's a terror attack, and that's what it will be called as long as its determined that the shooter was not completely mentally insane. As long as he had some semblance of his wits about him, then he is a domestic terrorist. A terrorist spreads fear and, typically, a political message by attacking civilians.
The Columbine shooters probably shouldn't be classified as terrorists ---- same with Sandy Hook. Tim McVeigh was a [Caucasian] terrorist. We'll see why the fuck this psycho decided to carry out this attack. 90% chance that he is quickly labeled a domestic terrorist unless it comes out that he was just some loony bin escapee.
Either way, there should be another serious push for more gun regulation ---- how the hell did this guy get access to such firepower?