In the U.S there were 12,664 murders in 2011, of those 8,583 were caused by firearms, some of these crimes were committed by people who owned guns legally. On 2012 two major massacres took place, one was in the Aurora Colorado movie theater which was showing the new Batman movie, Man came in the theater and began shooting in to the crowd, 70 people were shot, 12 of them were killed. Also, in the Sandy Hook Elementary School in Connecticut, gunner opened fire inside a classroom; he shot 20 innocent kids and 6 adult staff. Tactical weapons, machine guns, shotguns, semiautomatic handguns and even smoke grenades, were used in these two events and allowed this terrorists kill and injure a big amount of people in a short period of time. All the weapons were acquired legally in guns stores in the US.
Guns laws should regulate sales, use of firearms and ammunition. The sales of grenade,