Another intruder drill

I don't know why but it always makes me sad when I hear that Zach's school did another intruder drill. His teacher is really really good about emailing things home to the parents and today she sent this :

We had our intruder drill this morning. Mrs. Mackey went over the
intercom and called for a "Code Red". At this time, the students went to
the corner near our sink and sat quietly on the floor. Shades were
lowered and closed. Our door was shut and the lights were turned out. I
placed a green piece of paper between the shades and window to signal "all
okay" and joined the students in the corner. We remained in this position
for about 5 minutes while a sweep of the building occurred. The students
handled the drill very well.

It just makes me sad thinking of my tiny guy huddled in a corner with his classmates even if it is only a drill.