Babies are born with the lust to appease their hunger like tiny birds, fresh out of the egg, quarreling for mothers' attention, breast, bugs, or whatever food is available. Now the scientists study the scene of carnage and breathe better knowing how much worse it might have been. They try to deduce through surveys, who might be the next shooter. Wow, any one of those is enough to propel a child of potential to a wasted life of mistakes. Taking a life has less meaning when you feel no value yourself.
Fate is always present, never pausing for rationality nor pity.
Remember the lovely writings of Rabbi Harold Kushner, whose first book When Bad Things Happen to Good People, attempted to supply the impossible answer, written after he had lost a young child, and he had looked differently at God. I think that any time you try to make sense of it, suggest that there might be some good coming out of it, that there's a reason for it, just invalidates the pain that the parents are feeling. What happened was evil, wrong, cruel. There's no morally acceptable reason for it. Any Christian or Jew who takes their faith seriously, has got to know that dumping on kids is a major violation of your faith.