April 20, 2009, marked the 10-year point since two students at a large, at a Colorado high school, walked onto the campus with the express intention of killing as many people as possible.

     Eric Harris and Dylan Klebold turned Columbine High School into a one-word metaphor for school violence. Prior to their armed assault, there had been other instances of student attacks, but nothing approaching the magnitude of Columbine.

     In the attack, the shooters planted bombs and concealed numerous weapons on their persons, then entered the campus during a busy lunch period. Although the bombs failed to detonate as the pair hoped they would, the two high school seniors killed 12 students and one teacher, and injured many more.

     Area law enforcement was soundly criticized for its response to the incident. Among the charges leveled by parents, residents and the press was that information about the two attackers, their penchant for violence and making threats, as well as their interest in bomb making, were known to investigators in advance of the school attack. Officials were also criticized in their handling of the scene when active shooters were present.

     As a result of the Columbine shootings, police protocol embraced more proactive responses, a development that has undoubtedly saved lives. But even though both school and law enforcement authorities are much more cognizant of the signs of potential problems, school violence has not been relegated to the past.

     On April 16, 2007, a mentally disturbed Virginia Polytechnic Institute and State University (Virginia Tech) student, Hui Cho, shot and killed 32 individuals on campus and wounded many others before finally committing suicide. Cho's rampage would result in the highest number of casualties in a school shooting in the history of this country.

     Other violent acts have also taken place since the Columbine massacre, including an incident in 2006 in which an adult took children in an Amish school hostage, then killed five girls, ages 6 to 13.

     Schools have long employed on-campus security measures that, particularly in high schools and middle schools, include school resource officers. But in this day and age of economic cutbacks, budget shortfalls and just plain hard times, departments and school systems need more than simply a school resource officer. They need inexpensive but effective ways to prevent these things from happening. Law Enforcement Technology took a look at some cost-effective ways schools, and the law enforcement agencies that patrol them, can help shut down potential problems before they grow. Here is what we found: