Yes, history is replete with people lined up to be shot and doing nothing...
Shock and fear can paralyze you, even if your brain is screaming "RUN" your legs don't move...
I also may add, we don't know where the shooter was positioned in the classroom, if he cut off any escape route, you know you are toast anyway...hoping help is coming before you are gone...
No way 20 people cannot take down one.
On a recent visit with my dog at the Vet, the Vet had trouble getting blood from my dog's leg. My dog was in panic mode, as he always is when I take him in. The vet said that adrenaline literally thickens the blood. I think your are correct that fear (excess adrenaline) can paralyze people. However, people need to be taught more to over come it.
I was once a robbery victim in a store in which I worked. A gang of armed blacks herded everyone, customers and employees into the back and made us all lie down and empty our pockets. Fortunately, no shooting occured. Since that time, i am always vigilant wherever I go. I always CCW. Even when I am sitting at home, i have my gun in my pocket, even in my pajamas.
I have only had to fire my gun once. My dog was attacked on a walk one evening by a pit bull. For a moment, I was too shocked to know what to do. I didn't want to use my gun in the middle of a residential neighborhood. But I reasoned that there was no way I was going to watch my dog be murdered while I had my .38 in my pocket. I shot the pit bull twice to make it drop my dog. He only suffered puncture wounds to the skin on the back of his neck. The damned pit-beast actually survived. Fear and shock are difficult to overcome, but sometimes we have to do it.
Just wondering why no one picked up a desk and charged at him. If one person started, others could have circled him and bashed his head with chairs or desks. That one veteran charged him with his body, and took lots of bullets for his bravery.
Kids today don't go to scouts or ROTC, or take any kind of thought to survival skills.