(CNN) - Thousand Oaks is supposed to be a safe place.
The Southern California city, where at least 12 people were killed in a shooting Wednesday night at a bar, is considered one of the safest cities in the nation.
"It's a residential community, very quiet, very conservative," Steve Moore, a former FBI Supervisory Special Agent, told CNN.
Thousand Oaks, with a population of about 130,000 people, is located 40 miles northwest of Los Angeles, in the foothills of the Santa Monica Mountains. It's an upscale town with a median household income of $108,290, well above the national average. It's a pretty place too, with more than 150,00 acres of greenspace within in the city limits.
Violent crime is so rare there that locals often joke police don't have much to do other than to give speeding tickets to drivers.
"We are consistently ranked one of the highest with respect to the lowest crime rate per capita; we're proud of that," Thousand Oaks mayor Andy Fox told CNN.
Locals feel safe enough there to forgo some of the routine precautions other city dwellers take. They leave their purses in their cars, leave their doors unlocked and their drinks unattended in a bar.
This safe oasis, with its proximity to Los Angeles, has attracted Hollywood stars, who've moved to the area with their families to live a "normal" life. Will Smith, Wayne Gretzky, Selena Gomez, Justin Bieber and others have been spotted in the stands at high school football games there, cheering on family and friends.
The bar was loved by adults of all ages
But that sense of tranquility was shattered Wednesday with the mass shooting at the Borderline Bar & Grill. Considered something of a community unto itself, the regulars at Borderline include a healthy mix of young adults looking to dance and flirt and middle aged regulars hoping to show off their line dancing or swing dancing skills.
The place has a relaxed, open vibe. There is a bar in the middle, a dance floor on one side and pool tables on the other.
Wednesday night is college night, when Borderline attracts students from nearby schools such as Pepperdine and California Lutheran University. On nights when it gets packed -- and college nights often are -- big industrial-size fans spin in the corners to help keep everyone cool.
Madeline Carr, news editor at the student paper the Pepperdine Graphic, knew some of those who were inside when the shooting started.
She told CNN the bar opens up to anyone over the age of 18 on Wednesdays and described it as a "fun spot for dancing."
"Pepperdine's a pretty small community, a pretty sheltered community ... so it's one of these events that it's hard to rationalize it happening here," she continued.
The residents worry things will never be the same
Resident now fear that this tragic, deadly shooting will change everything about the city they love so much.
"We're a little community. We're the safe haven," resident Betty Harrah told CNN. Her son witnessed the shooting.
"It's tragic that we're all experiencing this."
Fox, Thousand Oak's mayor, said in this day and age, mass shootings like this can strike anywhere.
"The reality is that these types of incidents can happen really at any place, at any time, even in communities that are considered extremely safe," he said.