This is the 4th "soft target" attack in 2 weeks

Wednesday night's shooting marked the fourth "soft target" attack in two weeks, raising questions about how to make these public spaces safer.

"Soft targets" represent simple, daily life. People come and go. They expect to be safe as they pick up a cup of coffee, deposit their paychecks, fill prescriptions or grab a bite to eat. Their guards are down.

America has faced the threat so many times -- at a theater in Aurora, California, at a concert in Las Vegas, at the Boston Marathon. Every school shooting is an attack on a soft target.

The death toll in the four recent incidents has been stunning, with 27 people slain:

Two shoppers gunned down October 24 in the parking lot and inside a Kroger in Jefferson, Kentucky.

Eleven people attending Shabbat services killed October 27 when an armed man walked into a Pittsburgh synagogue. Six people were wounded, including four responding police officers.

Two women, a physician and a college senior, shot to death November 2 inside a yoga studio in Tallahassee, Florida. The gunman wounded four other people.

And on Wednesday, 12 people killed and more than a dozen injured when a masked man opened fire inside a bar in Thousand Oaks, California..