OK here's a loaded question
Let me say right away this attack is horrible and this MF'er deserves the death penalty. My heart goes out to the families of the dead, and to the wounded.
That said, is it "terrorism" if the attack is against military personnel? I think it isn't - unless civilians were also deliberately murdered as well. The attacker was not an enemy soldier so I would think the best definition for him would be mass murderer.