THE INTERPRETER: It's a largely American phenomenon : According to the Gun Violence Archive, which compiles data from shooting incidents, a "mass shooting" is any incident in which a gunman ... shoots or kills four or more people in the same general time and location By that definition, according to the Gun Violence Archive, we have seen 307 mass shootings from January 1 to November 5. That averages to almost 7 mass shootings a week. : Americans own more guns than citizens of any other country Civilians in the United States own about 270 million guns, according to a 2007 report by the Switzerland-based Small Arms Survey. That's enough to arm every adult in the US and still have some weapons left over. And it makes America the No. 1 country in firearms per capita. Also, in more than half the American mass shooting cases, the shooter had more than one firearm. In global incidents, the shooter typically had only one gun.