Looks like from what the report made by CNN, one of the reporters did a walk though with court Jury members though the building. Based on the report of the the mass shooting at the school it appears it did not have any kind of door access security card sliders or number punch in key pads.
Anyone know if this is common in most schools in the united States?

I visited one college campus in Washington its doors have security access card security.

Also anyone heard of Computer Vision Ai "I am learning the code but its difficult" can be used to detect weapons that are pulled and it can alert security or, lock doors?

I have some sample of code and its only used for Long guns. It sees it, draws a box around the image of the gun. I included some Audio code so it work but its VERY CPU intensive so the streaming video is stuck in ram and the video processing is VERY slow.

Tried to use it on another video where criminals are pulling guns in a convenience store, but it did not work.