(CNN) -- A grocery store. A movie theater. A middle school. A high school. All seemingly safe places in our lives that in one week of unrelated gun violence proved anything but.
In Philadelphia Friday, two 15-year-old students were wounded when gunfire erupted in the gym at Delaware Valley Charter School, police said.
In Indiana on Wednesday, two women were shot to death by a man at Martin's Super Market, police said. The rampage ended with police shooting and killing 22-year-old Shawn Walter Bair, who may have been known by the victims.
In New Mexico on Tuesday, a 12-year-old student with a sawed off, 20-gauge pump shotgun opened fire in a crowded gym at Berrendo Middle School. Two students were seriously injured and a juvenile suspect was quickly in custody. It was the second middle-school shooting in three months.
In Florida on Monday, a 71-year-old retired cop shot and killed a movie-goer who was texting his daughter moments before a matinee of "Lone Survivor," police said. There were about 25 people in the theater. The wife of 43-year-old victim Chad Oulson was shot in the hand trying to defend him.
For the millions of Americans whose lives take them to school or the movies or the supermarket, the thought might linger: What if ...
But experts say that the individual tragedies of such situations notwithstanding, there is nothing new to worry about.
"These incidents still remain relatively rare," said J. Peter Blair, associate professor of criminal justice at Texas State University. "For the most part, we'll never directly experience one of them. It's safer now than it's been in a long time."
While violent crime increased just under 1% nationally in 2012, the trend for the last two decades has been steady decline. In the 1980s, crime peaked as a result of the crack cocaine epidemic. Beginning in the early 1990s, however, crime began to decline. In the decade since 2000, the nation's homicide rate declined to levels last seen in the mid-1960s, according to Bureau of Justice Statistics.
Still, the number of active shooter events -- defined as one or more persons whose primary motive is mass murder in a confined or populated area, not including gang and family-related shootings -- has risen somewhat in real numbers, but the numbers are small.
A recent report by the Advanced Law Enforcement Rapid Response Training Center found that the number of these types of mass shootings has increased: from an average of about five a year prior to 2009 to 15 in 2013.
"The least typical events become those we fear the most," said Bruce Shapiro, executive director of the Dart Center for Journalism & Trauma at Columbia University. "For good reason -- we do have a social contract that depends on feeling safe as we go about our everyday activities."
Shapiro was himself severely injured in a widely publicized 1994 mass stabbing at a coffee bar in New Haven, Connecticut. A mentally disturbed man sitting by himself pulled out a knife and stabbed or slashed seven people. The next year, Shapiro wrote about his experience in The Nation.
"We need to understand that the incidents of mass violence that are making our workplaces, movie theaters, schools, shopping malls more dangerous are consequence of specific political arguments, choices and debates that have playing out for generations," Shapiro said.
The reality is not that public spaces have become unsafe, Shapiro said. The escalation in mass shootings, often by mentally ill people, is directly related to what he said were irresponsible national policies on guns and treatment of the most mentally vulnerable citizens.
"What we haven't done as a society is go one step further and look at the escalating number of terrible mass shootings and say, 'How do we become a safer society?'" he said. "The vector for these events are, on the one hand, guns and, on the other, some toxic mix of mental illness and anger. Put those things together and you have Newtown, Columbine and Aurora. We need to deal with that."
Recent violent incidents have renewed public attention on a chronic shortage of beds for the mentally ill -- an alarming national trend that mental-health advocates say is responsible for a long list of violent acts.
Research from the nonprofit Treatment Advocacy Center found that the number of state psychiatric beds decreased nationwide by 14% from 2005 to 2010. In 2005, there were 50,509 state psychiatric beds, compared with 43,318 in 2010. In 1960, by comparison there were 535,000 public psychiatric beds nationwide.
The shortage of psychiatric beds dates back half a century to President John Kennedy's signing of the Community Mental Health Act in 1963. The goal was to shut down public psychiatric hospitals, replacing them with small community-based centers that never materialized, according to advocates.
Shapiro said the nation has failed to take an honest reckoning of the factors that make schools, malls and other public places more dangerous.
"It's not about our public spaces becoming less safe," he said. "It's about our failure as a society to honor our own social contract."
A net gain of the recent bloodshed is that Americans have become much more sensitive to mass trauma. Shapiro attributed the change to the fact the Americans collectively witnessed the 9/11 terror attacks and some of the carnage from the wars that followed.
"I think as a society we are much more aware and much more accepting of the idea that people can be changed, traumatized and wounded by exposure to violence. Everybody knows now what PTSD is," he said, referring to Post Traumatic Stress Disorder.
Still, every new report of a mass shooting takes Shapiro back to the night in 1994 when a deranged man stabbed him and six others in a New Haven coffeehouse.
"It was very fortunate that he had a knife and not a gun," he said. "I think about that every time I hear about one of these mass shootings."
The question of what makes a safe society is fundamental.
"You can't shoot your way into a safe society," he said.