(Denny Crane: "Sometimes you can only look for answers from God and failing that... and Fox News".)
They no longer trust students to go to their lockers, except first thing in the morning & last thing at the end of the day.
You should see what goes on inside of a school buildings these days. I had to pick one of my kids for an appointment & got caught in the middle of a practice lock down. They locked me in the office & called his classroom, to have him brought down. As we left the school police were coming in the front door with rifles & dogs. This was a short time *before* Columbine.