(Newly updated and tragically still relevant.)
According to the LA Times, since Sandy Hook there have been 144 shootings on school campuses across the nation, as well as numerous other acts of mass violence not on school grounds. If I reacted strongly to each time such a tragedy happened, I would not make it through the day.
Along with the death and pain from mass shootings, a huge number of people die and are injured in smaller altercations that have no need to escalate to deadly force. And adults and children are accidentally being injured and killed by weapons weekly.