Well, that is a firecode violation. The doors and windows on any public buildings have to be formidable enough to stand a fire for a certain period of town. Im not an expert on the issue, but most commercial and business type buildings Ive seen seem to be more formidable than your average household.That said, the doors and windows on the average building are still not "bullet-proof", but I have confidence they will slow an intruders entry better than your typical residence.
Ive been studying the various active shooter court-cases. Reading up and looking at whats available on the internet. Basically, it comes down to two active-shooter. The active-shooter who sprays rounds everywhere and the type which is more methodical. I think its a better strategy to develop a plan of action which is fight or flight and practicing these scenarios in a workplace. Obviously, the best plan is to try to escape, but there are times when fighting might be the best solution such as when all avenues of escape are blocked or you wish to go up against the active shooter to prevent them from shooting additional people.
I dont see the book bag as an option and would discourage its use. Im in Starbucks right now and what if someone came in shooting? It would be a waste of time to grab my bulletproof laptop bag, if it indeed were bulletproof, and use it as a shield. In that very short time I could have jumped behind cover or tried to fight the shooter. Maybe even flung the laptop bag at the attacker. Grabbing it, holding it over my head and that would be a total waste of time. That time being less than a second could be used to move which might make the difference between getting shot or escaping or making a defense against the attacker. Practice yourself with a paint ball gun. Try to put that bookbag over your face and see where your buddy decides to shoot next. While the bag is over your face, you will get nailed in the lower extremities whereas you might not get hit at all if you react reflexively and use that time to jump to cover or escape. That time probably being less than a second is all you need to move that short distance to cover or be on the move or hurling that bookbag in the air at the attacker.