This time, Cleveland.

A 14-year-old suspended high school student entered Cleveland's Success Tech Academy, a gun in each hand, and opened fire, wounding four. Later, we learn that the shooter's past included violent confrontations, mental problems and at least one previous suspension. A month earlier he told a friend that he intended to shoot up the school. But no one, apparently, took his behavior seriously enough to notify authorities.

Meanwhile, a high school teacher in Oregon, with a permit to carry a concealed weapon plus training, sought permission to carry her firearm to school. In fear of her ex-husband, against whom she filed and received two restraining orders, she wanted the ability to protect herself in the event he showed up. Furthermore, she argued that even without the fear of her ex-husband, the Second Amendment and Oregon state law allow her to carry her firearm to work. Her school district, however, prevents her from carrying a firearm to school.

This raises a question. Do shooters consider schools "gun-free zones"? Do they consider it unlikely that any authority figure -- whether teachers or, in some cases, security guards -- poses an armed threat? But in some school shooting cases, guns helped to end shooting sprees and minimize loss of life and injury.

Edinboro, Pennsylvania. A 14-year-old middle school student opened fire at a school graduation dance, being held at a local restaurant. The shooter killed one teacher and wounded two students and another teacher. The armed teenager was apprehended by the restaurant owner, who grabbed his own shotgun from his office and went after the shooter. Staring into the owner's shotgun, the teen dropped his gun and surrendered.

Pearl, Mississippi. A 16-year-old sophomore entered Pearl High with a hunting rifle under his overcoat. He opened fire, killing two students and wounding seven. The assistant principal, Joel Myrick, ran to his truck and retrieved the .45 automatic he kept there. Running back, he spotted the shooter in the parking lot. Ordering the teen to stop, the vice principal put his gun to the shooter's neck and held him until police arrived. Continued...