Given that the number of gamers worldwide who have played or presently play violent video games is roughly estimated to be somewhere around 250 million, and the number of shootings, school shootings and violent crimes associated with violent video games is (roughly) 10-20 per year....
Would that not suggest that there is some alternative explanation for these outbursts of violence than the video games?
In fact, there's a far stronger correlation between violent crimes and eating carrots, or riding bicycles than there is for video games.
Besides, didn't we used to blame these shootings on television? When did we stop blaming TV for violent crimes?