This is probably as good a time as any to link to my colleague Jeff Goldberg's piece which argues for more gun safety measures along with a larger portion of the citizenry bearing firearms. You can read Jeff's update to his article here. Among his points:
People should have the ability to defend themselves. Mass shootings take many lives in part because no one is firing back at the shooters. The shooters in recent massacres have had many minutes to complete their evil work, while their victims cower under desks or in closets. One response to the tragic reality that we are a gun-saturated country is to understand that law-abiding, well-trained, non-criminal, wholly sane citizens who are screened by the government have a role to play in their own self-defense, and in the defense of others (read The Atlantic article to see how one armed school administrator stopped a mass shooting in Pearl Mississippi). I don't know anything more than anyone else about the shooting in Connecticut at the moment, but it seems fairly obvious that there was no one at or near the school who could have tried to fight back.