The tragedy at Northern Illinois University yesterday has prompted new debate over how to control gun violence.
Consider this: Since the beginning of February, there have been seven incidents in this country in which three or more people were killed by guns, a total of 32 people.
During the past year alone, there were the City Council shootings near St. Louis, the violence in a Lane Bryant store outside Chicago, the Omaha mall shootings and, now, another school massacre, less than one year after the tragedy at Virginia Tech.
After each incident, the same overriding question remains: How could it happen? And, what can we do to prevent this from happening?
We learned today that the student gunman at NIU bought his four weapons legally, just like the shooter at Virginia Tech.
So, is the answer stricter gun control?
Second amendment advocates say no.
But even those who say yes believe it would take years to clean up the illegal markets.
"It's incredibly easy for anyone who wants to get a gun to get a gun," said professor Delbert Elliott, director of the Center for the Study and Prevention of Violence, which is part of the Institute of Behavioral Science at the University of Colorado, Boulder.
The NIU gunman reportedly stopped taking medication, and the Virginia Tech gunman had a long history of mental health issues.
"In virtually all cases, there are some warning signs," Elliott said. "In some cases, it's a clear warning, in others, it's more difficult."
But there are thousands of college students who now say those warning signs are being missed. They want guns, themselves.
Approximately 12,000 students have joined a growing group on Facebook, calling for concealed guns on campus.
One member, Mike Guzman, is a junior at Texas State University. He said he can carry his gun to the mall and to the movies, but not to school.
"Right now, all the recourse they have is to hide under a desk and pray that they'll make it out alive," Guzman said.
But the vast majority of schools say that's not the answer, nor can you turn campuses or malls into armed fortresses.
But Johns Hopkins University did do something. They hired a former Secret Service agent to create a state-of-the-art system called "smart TV" surveillance.
It's "a computer program that looks for potentially suspicious activity, somebody ... acting erratically in some way," explained Dennis O'Shea, executive director of communications and public affairs at Johns Hopkins. "When that happens, the monitor's attention is called to that camera."
The university says crime has dropped 43 percent since it installed the cameras.
But it's questionable as to whether even the "smartest" surveillance could have prevented this week's campus attack, last week's shootings or last year's massacre.
Authorities say, most likely not.