When things like this happen make sure you remember the trends of human history. Crime, war, and other horrible things have been on a gradual decline. Social media makes it seem like there is a increase of crime and terror but its actually just increase in reporting- and reported in a much negative light usually. Of course, that doesn't mean anything to the family members to potentially victims but for the rest of us, remember that please.
Hopefully everyone recovers alright from this truly tragic incident.