J.O.
How old is your son? Do the kids watch any TV or movies understand the difference from fantasy and reality? While I would like to keep all violence from my children too I know that without knowing that sometimes those types things happen in the real world they would be unprepared for life. We tell our children fairy tales like red riding hood to in order to introduce bad guys and that get what they deserve in the end. So talking with them about the video games and how they are not real and someone made up that story for a game is very important. Having an open dialogue with them is important way to bring the morals and beliefs you want your children to have. Good Luck!
J.