BILL WEIR: This is the worst American mass murder since the Virginia Tech shootings two years ago this month, and if you put it in context, and look at this graph. The numbers are truly stunning. Since the 1930s, incidents of mass murder – defined as the killing of four or more people – have risen steadily decade by decade. Major upswing in the last 20 years. So far this decade, 28 mass murders. The common denominator in all of these, guns. More than 250 million legally registered guns in this country. No telling how many more there are illegally out there.
DAVID MUIR: With this gun violence in Binghamton and Pittsburgh, 44 people have now died in mass shootings in this country in just the past month. It's been said over and over again that guns are more easily available here in the U.S. than in other Western countries, but is that playing a role? Our senior justice correspondent Pierre Thomas tonight with that part of the story.
PIERRE THOMAS: Mass shootings are occurring with frightening frequency. On March 10, a gunman fired 200 rounds, killing 10 in a Sampson, Alabama, shooting spree. March 21, about a week later, four California police officers shot to death. Eight days later, March 29, a gunman executes eight people at a nursing home in cold blood. Then, the very same day, six dead after a man fatally shoots five family members before killing himself. Today Pittsburgh, yesterday Binghamton.
BARACK OBAMA: I am heartbroken for the families who survived this tragedy, and it just underscores the degree to which, in each of our countries, we have to guard against the kind of senseless violence that the tragedy represents.
THOMAS: Since the Virginia Tech massacre, there have been at least 50 mass shootings where three or more people were killed. Total dead: more than 200. And with more than 250 million guns already in circulation, figuring out what to do about the gun violence is not an easy task.
PROFESSOR JAMES FOX, NORTHEASTERN UNIVERSITY: We have a downturned economy, we have people losing jobs, an eclipse of community, people are angry, they want vengeance. And that, unfortunately, there are plenty of guns out there for them to acquire legally or illegally to get the kind of satisfaction that they seek.

THOMAS: David, even with all that carnage, there's no major gun control legislation pending before Congress.
MUIR: Pierre, we did hear the President talk as a candidate about gun control. Have we heard anything from the administration now that he's President?
THOMAS: Well, there's been some talk of taking another look at the assault weapons ban, which was allowed to expire, but it's fair to say that since the administration took office, no urgency on gun control.
MUIR: All right, Pierre Thomas from the news room of our affiliate in Lynchburg, Virginia., tonight. Pierre, thank you. And we wanted to note that next Friday, the result of a year-long ABC News investigation. I team up with Diane Sawyer, as we ask: How do you defend yourself in cases like these if an intruder bursts in? Our hidden cameras arranged by police, and we ask: After Columbine and Virginia Tech, were lessons learned? Were promises kept? That's next Friday on a special 20https://cdn.newsbusters.org/images/20.