The point is that laws should be ammended to better accommodate the needs of the current world. Firearms like these shouldn't be accissible this easily, and their usage shouldn't be glorified to this degree. I understand it may be a part of your heritage for many of you but making them this easy to get makes it more probable that mentally sick people would get them and the chances of violence like this happening increases manyfold. The regulations should be stricter and usage should be heavily restiricted. It is not impossible to implement. Many countries have regulations and on average they seem to work pretty well. Ofcourse incidents like this happen, but they're much less in frequency that in the States.
I'm from a rural area and large cities probably shouldn't have our gun laws (we barely have any). In any case, gun control may work well in other nations where owning guns has not been a civilian thing since the birth of their nation and where gun regulation has always existed in greater amounts. Here in the US we are the worlds largest arms producer and we have countless guns that cannot be tracked. In my state you don't even have to register a gun and nobody has to know it exists. Now we actually have experimented with tighter gun regulations. Like in California and urban areas where gun control is far more strict than a rural area. However people in these urban areas still get guns and still kill people with those guns. Even felons as KH pointed out. Tighter gun regulation doesn't seem to prevent determined people from getting guns. At best it can stop someone with no street smarts or connections. Not only that but a determined person can kill with all sorts of shit. Like the Tsarnaev brothers or those two guys who hacked up that British soldier. If someone is determined that they are going to do a mass killing, they're gonna do it with or without guns.
I think the real issue with most gun violence in the US is culture, lack of opportunity and lack of education. Perhaps not in this case though.