I just ask a few straightforard questions, myself.
Was the target civilian or military?
Was the perp invoking his religion as a motivating factor, or was the religion involved nominal?
"did the perp exhibit any behavior before hand that exhibited sympathies or support for terrorism in general, or a specific form thereof?
"does the perp have known connections to terrorist groups?
In answering these questions for the thing that went berserk, the answers would be "military", "yes", "yes" and "we don't know yet but quite possibly no".
I wouldn't say that ALL these criteria would need to be met, but the first one, alone, disqualifies the act from being considered terrorist. Considering the yes answers, though, I would tend to classify it as Jihadist guerilla war carried out by a lone individual -- a distinction that does not make the victims any less dead, mind you.
I really do not understand much of the apologia that arises whenever these sorts of events are discussed, but when a thing such as this expresses support for Islamic based terrorism and invokes Allah during their blood bath, it seems the height of sophistry to me to try to remove Islam from the equation with such a surgical precision that it did not contribute at all. Sure, those who indulge in such sophistry think they are defending those Muslims who do not share these arch views, but through such obfuscation, all people are revealing is tha they are reactionaries. They are reacting to those who might conflate terrorism with Islam to such a degree that they are synonymous , but simply crafting themselves as the mirror image thereof.