Yes, comparing crime rates, including mass shootings, in one place against rates in another place, is valid - if you truely want to understand the causes and change things.
Only a leftist would deny it.
At first I thought this was a school in Mexico - for obvious reasons.
In this case it’s pretty clear the 18 yr. old has had issues for a long time. Didn’t attend classes at school, unconcerend about his appearences. And apparently little parental envolvement. So first thing he did at 18 was buy guns and ammo.... He was bound for something destructive.