No idea how close he was to completing his technology, but one of the victims was working on an engine that runs on water

The cops outside for (1 or 2?) hours allowing the shooter to take more lives, pinning a parent down and some had tasers out

Why wouldn't the police attempt to save lives? I first heard that a border patrol agent didn't wait for backup and went in lone wolf style and took out the shooter. Border patrol agent is said to have sustained (minor?) leg injury but source only suggested that it was either from a gunshot or shrapnel as a result of the shootout. Border patrol agent was apparently able to walk out of the school.

I read that this school already had checkpoints and a system in place and questions raised about how this shooter got in in the first place?

Expensive guns used; minor point but I remember someone pointing out that the gun(s) used aren't cheap and wondering how an 18 year old has guns like these