Shooter is shot dead and can't be questioned. Many children are dead.
18 is 6 + 6 + 6 just like the last shooter.
If another 18 year old pulls a similar stunt, they will have created this matrix:
6 + 6 + 6
6 + 6 + 6
6 + 6 + 6
https://edition.cnn.com/us/live-news/texas-elementary-school-shooting-05-24-22/index.html