There are more than 38,000 gun deaths in the US every year, and approximately 85,000 non-fatal injuries.
Despite some restrictions on gun research, scientists have sought to evaluate how certain policies affect gun deaths.
Policies that seem to reduce rates of gun violence include stricter background checks, limiting access to dangerous weapons, and prohibiting domestic abusers from owning weapons.
On Sunday, a gunman opened fire at a Madden NFL video game tournament in Jacksonville, Florida. The shooter killed at least two victims and himself, and shot at least nine others.
As the country tries to figure out what — if anything — can be done in the wake of yet another mass shooting, it's worth taking a look at the evidence we have on the effects of gun regulations.
There are close to as many guns in the US as there are people. There may be more, or there may be fewer, depending on which study you look at — there's no exact count, since there isn't a national database of gun purchases or firearm owners, and federal law does not require a prospective gun owner to get a license or permit.
That's one of the many obstacles researchers come up against when trying to evaluate why so many people die from guns in the US.
But what they do know is that the number of gun deaths in the US is incredibly high. Most of these deaths are not from mass shootings, but from firearm suicides and murders. According to the American Public Health Association, guns kill more than 38,000 people per year and cause approximately 85,000 non-fatal injuries.
There's still a lot we don't know about this recent recent shooting, including whether the shooter purchased his weapon legally or if any common policy recommendations would have stopped him from obtaining a weapon.
Yet we do have evidence on effective policies that could have helped prevent some incidents. Despite some congressional limitations on gun research, scientists have sought to evaluate the effects of gun-control legislation in the US and in other places around the world.