As I've already pointed out, this incident (whatever happened) has struck fear right across the developed world. So if it was a terrorist attack with that objective, it has very much succeeded.
Btw, I grew up in a place and time where terrorist attacks were common. To suggest they are always targeted at specific groups of people is unbelievably naive. Often they just want to generate fear and unrest, and the victims are indeed just caught up in it by random chance.
Anyway, my point is that no-one here has enough info to rule anything in or out. I find it bizarre how people can get so insistent that something could not have happened, when in fact they have no idea.