But that is not the full story. Gun deaths have actually been on the decline for the past 20 years, though mass shootings, as a proportion of overall gun homicides, are up slightly.
Monday's attack, which left 13 people dead, including the shooter, is the fifth mass shooting in the U.S. this year, a series of rampages that have killed a total of 35 innocent people. And if recent years are any indication, those 12 victims from Monday will be among about 10,000 to die by gun violence in the U.S. this year alone.
Coupled with the fact that the U.S. has more civilian firearms, both in total numbers and per capita than any other nation, these incidents have helped fuel perceptions of crime that isn't always accurate.
Here's a look at what the numbers tell us.
Gun homicides along with other violent gun crimes are "strikingly lower" today than during their high period in the mid-1990s, according to the Pew Research Centre
The peak happened in 1993 with 17,075 firearms-related homicides. By 2010, the gun homicide rate was 49 per cent lower.
However, nearly all of the decline happened during the 1990s and plateaued in 2001. In 2007, another downturn began again, albeit slower this time.
The number of people killed by guns is still quite high. In 2010, the Centre for Disease Control and Prevention, which examines death certificates, counted 11,078 gun homicides in the U.S. for that year.
A survey by the Pew Centre earlier this year found that 56 per cent of Americans polled believed that gun crime is higher now than two decades ago. Only 12 per cent correctly thought that gun crime was lower.
The poll came at a time when the United States had just suffered through two of its most high-profile mass shootings — in a movie theatre in Aurora, Col., in July 2012, which left 12 people dead and 70 injured, and the shooting last December at an elementary school in Newtown, Conn., in which 20 students and six staff were killed.
University of Toronto sociologist Jennifer Carlson said there’s a perception that mass shootings — often the most high-profile of gun-related murders — happen like clockwork every few months, often because they dominate headlines for a lengthy time.
"These high-profile events are not only reported on the news, but they’re unpacked, dissected and talked about at length, and they kind of overpower any other narratives that are maybe less sexy," said Carlson, who moved recently from the U.S. to work at the University of Toronto.
"People are thinking, even though crime’s down, crime still happens. There’s that horrible thing I heard on the nightly news."
A large chunk of local news in the U.S. is devoted to crime, according to another study by Pew. Crime stories take up 17 per cent of total time for TV broadcasts, with only traffic and weather topping it.
Mass killings — defined as those where at least three people died — account for less than one per cent of all homicide deaths from 1980 to 2008, according to the Bureau of Justice statistics.
Most of these are shootings, but not all. Worth noting is that while a small percentage of killings, mass homicides have risen from representing 0.5 per cent (half a per cent) of all murders in 1980 to 0.8 per cent in 2008.
More than three-quarters of gun homicide victims are male. A disproportionate of those killed by gun violence are black. African-Americans account for 55 per cent of U.S. gun deaths despite representing only 13 per cent of the population, according to 2010 figures.
Nearly 70 per cent of gun homicide victims are in the 18 to 40 age bracket, even though that group only represents a third of the population. The highest number of victims are in the 18 to 24 year-old range.
No one knows why the rate of gun homicide has dropped over the past 20 years. There is some consensus that it may simply be a matter of demographics. The Pew Research Centre notes that the large post-war baby boom created a lot of people aged 15 to 20, a high-crime age bracket, in the 1960s and 1970s, which contributed to a rise in crime.
Some of the more controversial reasons suggested by researchers relate to abortion and lead exposure. One theory that has been floated is that the 1973 legalization of abortion resulted in a decrease in the number of unwanted children, a cohort that might be considered at higher risk of turning criminal.
Another is that a reduction in the use of lead in gasoline during the 1970s reduced exposure to a substance that can cause brain damage and possibly violent behaviour. Most scientists have discounted both ideas.
According to 2009 data collected by the UN Office on Drugs and Crime (UNODC), the U.S. sees 3.3 homicides by firearm for every 100,000 citizens. By comparison, Canada's rate is 0.5 homicides and the U.K. is 0.1. Most European countries sit somewhere in the same range.
China and Russia are not in the UNODC roundup, and there are many countries in Central and South America, the Caribbean and parts of Africa that have much higher rates than the U.S. Mexico, for example, has three times the U.S. rate for gun homicides according to UNODC data. In Colombia and Venezuela, the rates per 100,000 are 27 and 38.9 respectively. In South Africa, it is 17.03 gun homicide deaths per 100,000 people.