Not sure on that, but a lot of schools have large exterior windows made of shatter resistant glass, the kind with embedded mesh. I don’t know if this school had that... it certainly didn’t next to the external doors.
Also, as noted in the hearing, the police chief did think about doing that... over an hour after the shooter entered the classrooms.
I watched the entire Donut Operator video, thanks.
That “police chief” (LOL) needed to be relieved of command in the first ten minutes.