If you read The Second Amendment carefully it is quite clear that it permits "the people", ie the State, to raise a militia in the country's defence. This because that, at the time the constitution was drawn up, there was no standing army. It is not a licence for private individuals to carry arms. Of course no one takes a blind bit of notice.
Exactly...
But it isn't an argument that goes down very well in much of the USA.
The suggestion that in order to have a gun membership of the National Guard is mandatory is also unwelcome.
The USA is awash with guns. As long as this continues these sort of incidents will happen.