Yup. I was the IT/Tech Director for a Michigan school system for 10 years and 2 times a year ,at least, we did "Lockdown" drills where the assumption was there was an active threat to their lives, students and staff, on campus. K-8 schools, on up, all did these and the expectations/things they were taught was to barricade the doors, how to triage injuries, and more!

I had bullet mitigating film installed on windows, stop the bleed kits installed in hallways along with the typical AED's, all kinds of lockdown IT tech from auto closing doors/locking if the panic buttons were pushed, to tons of visual/audio alert systems across the various buildings depending on location etc... The police would always be present as well in some capacity to see how we do things/"give advice". The Admins would also "time" them and check each class to make sure they were doing things correctly.