Numerous people are reportedly dead in a shooting on the campus of a community college in rural Oregon. It's the latest incident of gun violence in a series this year, including a shooting at a movie theater in Lafayette, La. and another at a church in Charleston, S.C.

It is not yet clear how many people have been killed in Thursday morning's incident at Umqua Community College in Douglas County or the full circumstances of the shooting.

In this post, adapted from previous versions after mass killings in the past, we explore America's unique role among advanced countries as a place where support for guns is widespread -- as is violence involving firearms. There are some perhaps surprising findings -- gun ownership in the United States is declining overall, for instance. But although mass killings have occurred with increasing frequency in recent years, support for gun rights is still resolute in America.

Here are answers to a few questions you might have about guns and mass shootings, including:

 1. Shooting sprees are not rare in the United States. 

Mother Jones tracked and mapped shooting sprees over the three decades from 1982 to May of last year. They counted "at least 61 mass murders carried out with firearms across the country, with the killings unfolding in 30 states from Massachusetts to Hawaii," they found.

A Congressional Research Service report published in 2013 counted 78 incidents over roughly the same period, in which 547 were killed. Definitions of mass shootings vary. The report excludes those for whom terrorist ideology or criminal profit was a motivation. The Mother Jones staff limited themselves to indiscriminate killings of at least four people in public places by lone shooters.

It's too early to say how this latest incident will alter the counts.

In most cases, the Mother Jones staff found, the killers had obtained their weapons legally: 

2. Gun ownership in the United States is declining overall, but nearly a third of households still have a gun.

The General Social Survey has been asking Americans about whether they have a gun in their home for decades, and last year essential tied the record low level of gun ownership reached in 2010. As you can see the chart below, 31 percent of adults reporting having a firearm in their household in 2014. That is 17 percentage points below the peak gun ownership from 1977 to 1980.

Survey data released last year by the Pew Research Center broke down the demographics of gun ownership more broadly. They wrote:

Overall, about a third of all Americans with children under 18 at home have a gun in their household, including 34% of families with children younger than 12. That’s nearly identical to the share of childless adults or those with older children who have a firearm at home.
The new research also suggests a paradox: While blacks are significantly more likely than whites to be gun homicide victims, blacks are only about half as likely as whites to have a firearm in their home (41% vs. 19%). Hispanics are less likely than blacks to be gun homicide victims and half as likely as whites to have a gun at home (20%).

Pew found that gun ownership is concentrated among older adults, rural residents, and whites, especially white Southerners. Whites in the South are more likely to own guns than whites in other regions.

Authorities have yet to identify the shooter or shooters in Thursday's incident.

 3. Active shooter events have become more common in recent years.

A report published by the FBI last year, studying active shooting situations between 2000 and 2013, found that these kinds of incidents were happening more and more recently. The first seven years of the study found an average of 6.4 active shootings per year, while the last seven years of the study found that number jumped up to 16.4 incidents per year.

Active shooting incidents are defined by federal agencies as "an individual actively engaged in killing or attempting to kill people in a confined and populated area." (This is different from mass killings, which are episodes in which three or more people are killed, according to the FBI. While many active shooting incidents wind up being mass killings, more than half of the episodes in the FBI study did not meet that definition.)

 4. Of the 12 deadliest shootings in the United States, at least half happened after 2007.

As this map by The Washington Post shows, several of the deadliest shootings ever in the United States have happened in just the past few years -- including the massacres at Sandy Hook Elementary School in Newtown, Conn. and at Virginia Polytechnic Institute and State University in Blacksburg. These were the two shootings that claimed the most lives, and the third deadliest shooting was in 1991 in Killeen, Tex.

 5. America is an unusually violent country. But we're not as violent as we used to be.

Kieran Healy, a sociologist at Duke University, made this graph of deaths due to assault in the United States and other developed countries. We are a clear outlier -- along with Estonia and Mexico. Yet this country is a far less violent place than it was 40 years ago, with the rate of deaths due to assault declining by roughly half.

As Healy writes, "The most striking features of the data are (1) how much more violent the U.S. is than other OECD countries (except possibly Estonia and Mexico, not shown here), and (2) the degree of change—and recently, decline—there has been in the U.S. time series considered by itself."

 6. The South is the most violent region in the United States.

In a subsequent post, Healy looked at deaths due to assault in different regions of the country. Just as the United States is a clear outlier in the international context, the South is a clear outlier in the national context:

 7. More guns tend to mean more homicide.

The Harvard Injury Control Research Center assessed the literature on guns and homicide and found that there's substantial evidence that indicates more guns means more murders.

This holds true whether you're looking at different countries or different states. Citations here.

 8. States with stricter gun control laws have fewer deaths from gun-related violence.

In 2011, economist Richard Florida dove deep into the correlations between gun deaths and other kinds of social indicators. Some of what he found was, perhaps, unexpected: Higher populations, more stress, more immigrants, and more mental illness were not correlated with more deaths from gun violence. But one thing he found was, perhaps, perfectly predictable: States with tighter gun control laws appear to have fewer gun-related deaths. The disclaimer here is that correlation is not causation. But correlations can be suggestive:

"The map overlays the map of firearm deaths above with gun control restrictions by state," Florida wrote in 2012. "It highlights states which have one of three gun control restrictions in place - assault weapons' bans, trigger locks, or safe storage requirements. Firearm deaths are significantly lower in states with stricter gun control legislation. Though the sample sizes are small, we find substantial negative correlations between firearm deaths and states that ban assault weapons (-.45), require trigger locks (-.42), and mandate safe storage requirements for guns (-.48)."

 9. Gun control, in general, has not been politically popular -- and its popularity has been declining lately.

Since 1990, Gallup has been asking Americans whether they think gun control laws should be stricter.

The answer, increasingly, is that they don't.

"Less than half of Americans, 47%, say they favor stricter laws covering the sale of firearms, similar to views found last year," Gallup says. "But this percentage is significantly below the 58% recorded in 2012 after the school shooting in Newtown, Connecticut, spurred a nationwide debate about the possibility of more stringent gun control laws. Thirty-eight percent of Americans say these laws should be kept as they are now, and 14% say they should be made less strict."

 10. While general gun control isn't that popular, particular policies are.

While many Americans strongly support the right to bear arms, they also support specific restrictions, such as background checks, assault weapons bans and a federal database to track guns. Here's 2013 data from Pew Research Center.

 11. Shootings don't tend to substantially affect views on gun control.

That is what the Pew Research Center found after polling Americans after mass shootings in the United States. In fact, Pew reported late last year that for the first in more than 20 years, Americans showed more support for gun rights than gun control. That's what Pew found after Newtown.

And before other mass shootings, as well:

In fact, more people say gun ownership protects people from a crime.

*Earlier versions of this post were authored by Ezra Klein and Zachary Goldfarb, with contributions from Mark Berman.