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.

Grundy, Virginia. At Appalachian Law School, a disgruntled student on the verge of his second suspension entered a school building and shot and killed the dean and a professor. He then shot four students, killing one. Hearing the shots fired, two students, Michael Gross and Tracy Bridges, ran to their cars to retrieve their guns. With guns aimed at the shooter, Bridges ordered him to drop his weapon. When the shooter turned and saw Bridges' gun, he laid down his weapon and put his hands in the air. (My pro-Second Amendment documentary, "Michael and Me," goes into detail about this incident, as well as others.)

Professor and economist John Lott checked 280 separate news stories in the week after the Appalachian Law School shooting, and only found four that mentioned the students who stopped the shooter had guns. The Washington Post, for example, said the students "helped subdue" the killer. Newsday wrote the shooter was "restrained by students." The Richmond (Va.) Times-Dispatch, however, wrote that the shooter "was wrestled to the ground by fellow students, one of whom aimed his own revolver at [the killer]." Four months later, the Times-Dispatch detailed the students' actions, including the second student's use of a gun.

What do felons think about an armed citizenry? A survey of convicted felons by the National Institute of Justice found 74 percent of the felons agreed that, "One reason burglars avoid houses when people are home is that they fear being shot during the crime." The survey also asked these felons whether they had abandoned at least one crime because they feared the intended victim might be armed. Thirty-nine percent said they abandoned at least one crime; 8 percent had abandoned such a crime "many" times; 34 percent admitted being "scared off, shot at, wounded, or captured by an armed victim"; and nearly 70 percent knew a "colleague" who had abandoned a crime, been scared off, been shot at, wounded or captured by a victim packing heat.

A survey of 23,113 police chiefs and sheriffs across the country found that 62 percent of these top cops agreed that "a national concealed handgun permit would reduce rates of violent crime." About 80 percent of rank-and-file police officers, according to polls, support the right of trained citizens to carry concealed weapons.

Israel gets it. Since the 1970s, on school campuses in Israel, policy requires teachers and parent aides to arm themselves with semi-automatic weapons. The result? School shootings have plummeted to zero.

As for Cleveland, would allowing authority figures to arm themselves have resulted in reduced casualties, or perhaps even deterred the shooter in the first place? No one can say for sure. But no doubt at least some Cleveland parents now believe the benefits of armed campus adults outweigh the costs.