One of the founding principles of the US was the right of its citizenry to protect itself from the overreach of the government, which was enabled partly through the right for citizens to own firearms and other weapons. They're a means of self defense, but more importantly as a way to keep the gov in check. No government can control millions of armed citizens--which is exactly the point.

Killing in response to being disarmed is probably one of the most "American" things its citizens could do.