The violence carried out in Jonestown was cult-suicide violence that resulted in 909 dead did not specifically target Congressman Leo Ryan for his ideological perspective or political positions. Peoples Temples fanatics who were escorting Ryan and others on the transport plane killed the congressman, three journalists, a defecting Temple member, while wounding nine others. This was carried out because Ryan, a critics of cults including L. Ron Hubbard's Scientology, was investigating the activities of the Temple/agricultural commune in Guyana that had become a cult posing a threat to the lives of US citizens.
The violence carried out by McVeigh and Nichols in April 19, 1995 at the Alfred P. Murrah Federal Building that killed 168 people did not target any specific politician. The McVeigh-Nichols bombing in Oklahoma City falls into the same broader category as 9/11. In both cases, one domestic the other carried out foreign operatives intended to drive across a political message by killing any number of people at random. Media publicity by making a big splash was the goal, not the assassination of an individual politician whose policies were deemed unacceptable.
Racial, ethnic, and religious violence where people are targeted because they are a minority against which an individual or group is targeting for extreme prejudice is yet another category of sociopolitical violence. Labor and student violence that starts in the form of protest but ends up violently in clashes with police and/or national guard is another form of sociopolitical violence. Finally, street gang violence carried out by youth gangs and organized crime groups also falls in the category of sociopolitical violence. Invariably, certain rival gang, the police, or some entity in the political establishment is the target of gangs and/or organized crime violence.
In America's contemporary history, clearly 9/11 tops all categories of political violence in terms of its magnitude as a national tragedy and its impact on the nation. I doubt that the Arizona massacre will have the kind of lasting impact that 9/11 had on politics and society. Ernie Hunt citing A. Camus about the evil in the souls of men is appropriate to reflect, but Camus' observation seems to raise the question of whether people are born evil or if immoral society makes them so as Reinhold Niebuhr claimed. As much as I love the works of Camus, I would have to agree with Niebuhr whose pessimism led him toward a different direction than Camus to conclude that conflict and tension are permanent features of society and that power is the catalyst in claims between nations, races, and social classes.