Americans think the Internet shares almost as much blame for the massacre in Littleton, Colorado as the availability of guns, according to a Gallup poll study. The study, which was commissioned by NBC and The Wall Street Journal and released Friday, found that 82 percent of those polled blamed the Internet at least partly for causing the shootings, compared with 88 percent who blamed the accessibility of guns. Eric Harris, one of the two students who went on a shooting spree through their high school on April 20, had posted descriptions of making pipe bombs and violent messages on a Web site. Harris and Dylan Klebold shot up the school before taking their own lives, killing a dozen students and a teacher. The poll could indicate the coming of age of the Internet as yet another source of blame when tragedy erupts. Society has long searched for a cause of such grave incidents -- often pointing to movies or rock lyrics -- and with the shootings in Littleton, the Internet has joined those ranks. Critics of violent video games also have sought to pin blame for the massacre on bloody games such as Doom and Duke Nuke 'Em, which the killers played frequently. Participants in the Gallup poll placed an even heavier blame for the shootings on the killers' parents (94 percent); TV programs, movies, and music (94 percent); and social pressures on youth (92 percent). Pollsters surveyed 659 adults in the U.S. on April 21. Ben Bagdikian, former dean of the Berkeley School of Journalism and Washington Post editor, said the Internet should bear at least some of the blame because it provides a forum for threatening messages that could instigate violence. "The shootings don't have a single cause by any means, but there's no question that violence in the media has increased acceptance of aggressive behaviour," he said. "It's not enough to say 'you can't blame the Internet.' We've got to address some of these issues." Bagdikian said there are real-world rules that prohibit speech that indicates a "clear and present danger" to someone's safety, and those should also apply on the Internet, though he acknowledged that policing the Web is nearly impossible. Paul Saffo, a research fellow at the Institute for the Future, said the Internet and games that let a person take on the role of a killer played some role in the shootings. "Is the Internet the primary blame here? Absolutely not," he continued. "Does the Internet have to assume its place among inattentive parents, too-big schools, violent games and easily available guns? Absolutely." But free speech advocates point to the fact that killings and similar human tragedy took place long before the rise of the Internet. What's more, the Internet can provide a positive experienced for otherwise disenfranchised teens who are more comfortable behind a computer screen than at a school dance. It's also provided a cathartic outlet in the wake of the tragedy. Youths can chat about teen alienation on a new High School Underground site, or mourn the loss of friends on the Jefferson County schools site. "The Internet is becoming a mirror of our society," Saffo said. "It has equal helpings of bad and equal helpings of good."