Of course.
In the last several mass shootings in the States, about which we just had 18 pages of discussion, the root cause was terrorism (Baton Rouge, Dallas, Orlando, San Bernardino).
No it wasn't, it was AFAIK an act out of utter frustration. What you thought was the cause is in fact just another symptom, and that the problem lies much deeper within.
And yet you guys kept harping on about gun control. Misidentifying the cause as guns, instead of terrorism, surely ain't going to solve it better/faster.
Guns are symptoms as well (providing a false sense of security), the root cause is deeper.
As for this thread, we do not know enough details yet, although I saw a video clip where (one of) the perpetrator(s) was heard discussing with presumably a spectator of the developing scene before it went horribly wrong. The spectator said in German, "you're an ass-hole, you can't go shooting people in a mall", and the perpetrator said, "I will draw my gun", and "I am a German, I haven't done anything, shut your trap". Or words to that effect. I'd have to see/hear it again to be more accurate.
Cheers,
Bart