Are "lockdown" drills traumatizing schoolkids?

Catherine Crawford used to think so.

[R]epresentatives from the Department of Education unexpectedly showed up and announced that they would be conducting a special drill to prepare students in the event of a gunman in the building.... “All the kids were corralled in the block area out of sight, the classroom doors were locked, blinds drawn, and they all had to be quiet. They were so quiet. I couldn't believe it. Obviously they had done it before. Then, the DOE guys came and jiggled the door, kind of pretending to get in, and the kids had to stay quiet through that as well. You would have been really proud.”...

According to my 7-year old, it all felt like a game and was kind of “exhilarating” — her word.