She said that since its inception last year NeverAgainSoCal has garnered 200 to 300 members, the majority of them high school and college students.

Kimia Moehbi, 18, a student at Moorpark College, Ventura County, said Wednesday's killings, which happened "so close to home" had prompted people to face the seriousness of gun violence.

"This was definitely a call to action for a lot of people who have been living in such complacency," Moehbi said.

But both Robakowski and Moehbi said gun violence is a complex problem that does not lend itself to a single explanation.

"This issue is tied into so many others, and we still need to fix background checks across our nation. Even in California, there are still loopholes," Robakowski said.

California, a state with one of the toughest gun laws in the nation, has been the "poster child" of gun control, illustrated by some recent actions taken by state lawmakers.

These include passing legislation that raised the age for buying rifles and shotguns from 18 to 21 and imposing lifetime gun ownership bans on those convicted of domestic violence or who are involuntarily hospitalized for mental illness more than once a year.

Despite these regulations, questions remain. For example, the sale of the high-capacity magazine that Long used to kill his victims is illegal in California, prompting some observers to wonder how he had obtained the weapon.

Meanwhile, Thousand Oaks is having to cope with aftermath of the shootings.

Wind-whipped fires roared across Ventura County just a day after the killings, filling the air with smoke and forcing the evacuation of hundreds of thousands of residents.

On Friday, the scene of the shootings remained locked down by law enforcement officers, but occasionally people stopped by to mourn the victims and to add more fresh flowers to the piles that had already been left.

But like countless others in the US, they are still struggling to comprehend what prompted the shootings that shattered the tranquility of this normally safe area.

Delaney Dunlea, a 20-year-old who visited the scene on Friday with her friend Lauren Gunn— both students from Moorpark College —said, "We know half of the people who passed away, so it's just been crazy."

The most ironic aspect for local residents is that the bar was a communal gathering place for survivors of the Las Vegas Route 91 Harvest musical festival last year in which 58 people were killed.

Tanner Williams, 20, and Ryan McCarty, 19, both from nearby Simi Valley, were among a group of youngsters who stopped by the scene of the Thousand Oaks killings on Friday. Williams said he knew seven of the victims. His girlfriend, who was in the bar during the shootings, made it out alive.

Asked about his opinion on guns, Williams said the incident had changed his perspective on post-traumatic stress disorder, but not on gun violence.

"If everyone in the bar had concealed (guns), he might have gotten just a couple of people, but everyone would have just pulled out their guns and ended the threat there," he said.

No matter how strict the gun law is in California, people would figure a way around it, Williams added.

McCarty said: "It's a systematic problem in the US. I guess it's polarizing to everyone in the nation. To even change it would be a monumental thing."