More than one a day.
That is how often, on average, shootings that left four or more people injured or dead occurred in the United States this year, according to compilations of incidents derived from news reports.
Including the worst mass shooting of the year that unfolded horrifically on Wednesday in San Bernardino, California, a total of 462 people have died and 1,314 have been injured in earlier shootings, many of which occurred on streets or in public settings, the databases indicate.
It is impossible to know whether the number of such incidents has risen in recent years because the databases go back only a couple years. And experts fiercely debate whether mass shootings that involve four or more deaths are on the rise. Four or more dead is a standard used by congressional researchers and other experts who study mass killings.
Nonetheless, the stream of incidents this year — including an attack on a Planned Parenthood clinic in Colorado that left three dead last week and a shooting at a community college in Oregon that left 10 dead, including the gunman, in October — has intensified the debate over the accessibility of powerful firearms.
Two databases that track mass shootings — shootingtracker.com and gunviolencearchive.org — depend on news accounts and are not official. Nonetheless, they give an indication of the widespread nature of shootings that leave four or more people dead or injured. Since January, there have been at least 354 such incidents, according to shootingtracker.com.
Ted Alcorn, research director for Everytown for Gun Safety, a nonprofit organization that advocates gun control, said the incidents with multiple victims were just a small subset of everyday gun violence in America.
"You have 14 people dead in California and that's a horrible tragedy," he said. "But likely 88 other people died today from gun violence in the United States." In a recent report, the Congressional Research Service found a slight uptick in shootings in which four or more victims died. The report found an average of 22.4 mass shootings a year from 2009 to 2013, compared with 20.2 shooting in the previous five years.
But James Alan Fox, a criminologist at Northeastern University, said his research showed the number of such shootings has roughly held steady in recent decades.
He said that if you also included the data for 2014 from the same source that CRS used, and look at recent four-year intervals instead of five-year intervals, then the average number of annual mass shooting incidents actually declined slightly from 2011 to 2014, compared with the previous four-year period.
"It's a matter of how you slice it," said Fox, who praised the CRS report.
While the numbers oscillate from year to year, there has been no discernible trend either in the numbers or in the characteristics of the shooters, said Fox, who is also a co-author of "Extreme Killing: Understanding Serial and Mass Murder."
He said that changes in news media coverage and in the availability of news accounts of shootings have led many people believe that the number of shootings has been increasing.
But in fact, "the only increase has been in fear, and in the perception of an increase," he said. "A lot of that has been because of the nature of media coverage. In the '70s and '80s we didn't hear about it on the Internet — because there was no Internet — and we didn't have cable news channels that would devote 24 hours of coverage" then.
In an interview with CBS News shortly after the San Bernardino massacre, President Barack Obama said, "We have a pattern now of mass shootings in this country that has no parallel anywhere else in the world, and there's some steps we could take, not to eliminate every one of these mass shootings, but to improve the odds that they don't happen as frequently: common-sense gun safety laws, stronger background checks."
"We should never think that this is something that just happens in the ordinary course of events, because it doesn't happen with the same frequency in other countries," he added.