The recent masacre in Newtown CT, as "follow up" of previous masacres in high schools, colleges, movie theaters, shopping malls, churches, etc, will NOT be solved by arming the teachers and/or posting armed guards in all US schools.
This "solution" is impractical and extremely expensive and implies that college professors and priests also should carry guns and/or rely in the "protection" of more armed guards making things even worst. This type of "approach" will return the US to the uncivilized wild west.
The standing of societies that mainly serve the interests of the gun industry have blamed the masacres to video games, media, and mental health, and has ignored the role of easy access to high capacity magazines and semiautomatic weapons used in the masacre of innocent US citizens.