This is obviously a tragic event - mass killings of children and their teachers is truly shocking.
It would appear that the young man responsible was unbalanced, and as others have pointed out, being mentally unbalanced with access to guns compounds the damage that can be done.
I think there probably are more americans now who would like greater restrictions on gun or ammo ownership, due in part to the way these shocking events keep repeating themselves, but I doubt they are yet in a place where they would seriously consider repealing the right to bear arms - its part of their psyche, their DNA.
It cannot be just an issue of the availability of guns though - Some documentary I watched made the point that there were at least as many guns per head of the population in Canada, but deaths due to guns were nowhere near US levels. There is something in the combination of current gun laws, the amount of ammo you can have available, and the laws and mentality of US citizens that combine to such tragic effect.
Cannot remember who is was, but some commentator outside the US recently made the observation, flippant but grimly ironic in its timing, that "the right to bear arms makes as much sense as the right to arm bears"
http://en.wikipedia.org/wiki/List_of_countries_by_firearm-related_death_rate