According to an ABC special several years ago, there were over 31,000 gangs across the nation. The formation of gangs is most likely to occur in places where there is little money, few jobs and a lack of sufficient parenting. Unlike bombs and nuclear weapons, the gun can be easily hidden and acquired relatively easily. You can even buy a gun over the Internet, although the Federal Government is making efforts to make it harder for people without proper identification, etc. to buy one. There have been many incidents over the last 15 years where the police have used what many would consider excessive force to stop a person who is jeopardizing the welfare of the general public.
Toy guns look so identical to real ones that it's hard for a police officer to tell the difference.
An officer also has no way to tell if the weapon is loaded or not. By the time a cop does discover that the gun is fake, or not loaded, it's often too late. That's entirely true, but a fair number of gun owners aren't taking the precautions they should be taking so that guns don't get into the wrong hands. There have been more than enough examples in my opinion to show the NRA that some changes need to be made, before more and more innocent people die. Guns can be bought over the internet from more than a few locations and don't even require the buyer to show any form of identification.