The troubled man who killed six people and then himself in a rampage near a California university last week has sparked a flurry of online discussion on a wide array of topics: violence against women, gun control, mental health, even news coverage itself.

Some are typical of the reaction seen after previous mass shootings. But Elliot Rodger’s views expressed online in several ways — including a self-made “retribution” video for all to see — have struck a new nerve, different than some previous manifestos from notorious killers. The volume of material is sparking new reflections and adding a new complexity to pondering difficult questions raised after every mass killing: Why did this happen and how can we keep it from happening again?

“His actions have fostered a sense of helplessness and hopelessness that we are seeing played out on social networks,” said Dr. Ramani Durvasula, a psychology professor at California State University, Los Angeles who discussed the killings for an hour with college seniors in an abnormal psychology class on Tuesday. “So people are trying to understand it any way they can — and this time have more data that they can post and comment about.”

Rodger, 22, injured 13 others in the shooting and stabbing attacks Friday night in the small community of Isla Vista, adjacent to campus of the University of California, Santa Barbara. As news of the killings trickled out, discussion exploded online once people learned Rodger was suspected. People started sharing his video blogs and other posts.

One hashtag focusing on misogyny — #YesAllWomen — generated 1.6 million tweets in less than four days, with about 10 percent of the tweets directly naming Rodger, according to social media analytics website Topsy. Many of the tweets focused on the idea that Rodger’s hostility toward women is something many women experience in varied ways from men, even if those men don’t kill people.

“It’s not just this one guy — there are a number of people who think that way,” said 28-year-old Robyn Swirling of Washington, D.C., who on Saturday tweeted a picture of YouTube comments on one of Rodger’s videos, with people blaming women for his feelings of rejection. The tweet was retweeted more than 1,300 times.

“We’d like people to understand that this is all connected,” Swirling said.

The topic sparked two other hashtags and arguments between users with different views. Other discussions popular on Facebook and Reddit focused on mental health programs, gun control and continued news coverage of the attacks.

The conversations all morphed from Rodger’s trail of troubling views expressed in comments and other posts.

The community college student posted at least 22 video blogs, including the seven-minute “retribution” video that was taken down by YouTube but still garnered more than 2 million views on the site after being reposted by others. His other videos, still up on his YouTube channel, generated hundreds of thousands of views each. A 140-page manifesto he wrote was filled with clear hatred toward women, including an assertion that women should be confined to concentration camps. One of Rodger’s only two tweets — from an account that had five followers before his connection to the killings was revealed — had more than 500 retweets and nearly 300 favorites by Tuesday afternoon.

Dr. Pamela Rutledge, director of the Media Psychology Research Center in California, said the killings put a spotlight on things people don’t talk about very often just as they have become more comfortable having more meaningful conversations on social networks — even on issues surrounding mass killings in which there are no easy answers.

“Anytime something that’s unusual, that’s scary happens, we search for answers because we don’t want the world to be uncertain,” Rutledge said.

By making offensive comments about women, Rodger hit a nerve for people who often feel like women are misunderstood or mistreated, Rutledge said. “It gives us something to hang on to (in order) to try to make sense out of (an action) when we can’t make sense of the act,” she said.

Durvasula said the unprecedented amount of data in the Isla Vista killings means 10 different psychologists analyzing the situation could easily come up with different topics to examine.

“I’ve heard every possible (reason),” Durvasula said. “We’re all speculating because we have so much content.”