Very well said. Just one more thought - even if you are armed it might not help much in a situation like this. The students and professors in that building had no advance warning of the attack until the gunman opened fire. It was just an ordinary day, still fairly early in the morning. We can only try to imagine the panic that broke out when the victims suddenly realized they were under fire. Even if some of them had guns, how many would actually have managed to shoot back effectively?

Now, with the benefit of hindsight the victims could have fought back, guns or no guns. There was apparently just one gunman. He had to reload, he was shooting at close range and he was basically alone against several hundred people. If just one of the victims had the composure to strike or tackle him, smash him with a chair, fire extinguisher or whatever was at hand it would have ended the situation right away. But we know that didn't happen. Clearly, the fear and surprise was overwhelming. Nobody in that building was mentally in a position to fight back. If they had guns it might only have made everything worse. Spraying bullets at anything moving, causing friendly fire and more unnecessary fatalities. Without a proper mindset no weapon can do any good. And in the modern Western society most people are simply too out of touch with real world violence to react correctly under stress.