"Boys will be boys" is an apt quote here. A pedagogue friend of mine who I worked with for a while explained that kids and boys in particular have a biological need for, essentially, being violent. It is part of their physical maturing. While a lot of can be achieved through running, jumping, climbing and other physical activity, sometimes they just need a good dust up. Incidentally this was what we worked together on as I can make foam-weapons (everyone can make foam-weapons but it was a gig so get off my back). So suddenly the kids could run around wacking each other with little risk of actually hurting each other.
I remember this from when I was a kid as well. Every morning through kindergarten and first grade I would start my morning at a daycare center. We amused ourselves by wrestling. Not WWF wrestling but just trying to throw each other to the ground. The pedagogues did not try to break us up (though they did recommend we put some cushions on the floor), as it is generally understood that this sort of thing is a part of being a kid.
Now the article does talk about an increase in these events and if indeed that is the case then I don't think videogames can shirk at least its part of the blame. However it is not just videogames but a much broader problem. I believe it is more because of the increasing pace at which our world is moving combined with the glorification of violence in media in general (the stats with violent crimes going down while the coverage of violent crimes has gone up are on record) would make for a confusing world to navigate.
Humans have always had a need to point the finger and reasoned debate and coverage with the full picture don't sell papers (or ads if you will).
Lastly I would like to add: http://www.youtube.com/watch?feature=player_detailpage&v=3AOdIVJH7tE#t=246s