Some will be trying to make sense of a senseless horror. Others will be enraged, seeking vengeance on the guilty, and blaming those who failed to prevent it. The violence will be politicized, and leveraged for various agendas. Some will sadly use it for a religious agenda, claiming that this is God judging sin.
I would rather model my own response after the words of Jesus in a similar situation.
The people he walked with had the same impulse we have today. If something extraordinary and
horrifying happens, they want to make sense of it. When Galileans were slaughtered by Pilate, or when a tower collapsed, crushing bystanders to death, they resolved their uncertainties by suggesting that their horrible fates were somehow due to divine justice.
Jesus answered back this way: “Do you think that these Galileans were worse sinners than all the other Galileans, because they suffered in this way? No, I tell you; but unless you repent, you will all likewise perish. Or those eighteen on whom the tower in Siloam fell and killed them: do you think that they were worse offenders than all the others who lived in Jerusalem? No, I tell you; but unless you repent, you will all likewise perish.” (Luke 13:2-4)
He acknowledged that we will not always understand the “why” when things go wrong, we live in a broken world, after all. It wasn’t because the victims were “bad people”, because we are all bad people on some level. No. Instead, Jesus turned the attention away from being idle spectators into the fate of others, and turned it toward our own eternal state. Are we ready to face God, should it happen today? Are you?