The glass is an obvious piece of evidence.

What does it obviously show?

If it's a psyop why would you trust the official narrative?

It's not that mysterious. A guy shot a lot of young people, because they weren't sufficiently right wing to meet his idea of good for the future.

Do you even know about the multiple shooters?

There was one shooter. Breivik. He had a manifesto and everything. Nasty guy, but sad story overall. https://en.wikipedia.org/wiki/Anders_Behring_Breivik