Samuel Lerma, Arzetta Hodges and Desiree Qunitana join mourners taking in a vigil at El Paso High School after a mass shooting at a Walmart store in El Paso, Texas, U.S. August 3, 2019. REUTERS/Jose Luis Gonzalez
Mourners take part in a vigil at El Paso High School after a mass shooting at a Walmart store in El Paso, Texas, August 3, 2019.
Jose Luis Gonzalez/Reuters

On Tuesday, an 18-year-old man opened fire at an elementary school in Uvalde, Texas, killing 21 people, including 19 children.

A different 18-year-old man dressed in tactical gear and live-streamed on the internet shot and killed 10 people in a supermarket in Buffalo, New York, in what authorities described as a racially motivated mass shooting.

The US has seen 27 school shootings and more than 200 mass shootings by the year 2022, according to the Gun Violence Archive.

Scientific research doesn't support claims that mental health concerns are responsible for the rise in mass shootings over the past few decades. Mental health issues are not predictors of violence.

The number of gun deaths in the US is much higher than in other nations with similar rates of gun ownership, and certain policies can make this happen. Studies have shown that rules prohibiting domestic abusers from owning weapons, and securing firearms in the home, have a correlation with decreased gun deaths.

Switzerland has a stunningly high rate of gun ownership.

Here is what the data shows.

The scene of a mass shooting in Dayton, Ohio.
Bodies are removed from the scene of a mass shooting, August 4, 2019, in Dayton, Ohio.
John Minchillo / Associated Press

Background checks are not required when people buy guns from licensed dealers. According to research from the nonpartisan Rand Corporation, universal background checks could prevent 1,100 homicides per year.

In the US, 17 states and the District of Columbia have red-flag laws that allow family members and law enforcement to file Extreme Risk Protection Orders that restrict or temporarily remove a person's access to firearms if their behavior suggests they pose a violent threat.

In his recent remarks, President Trump endorsed those laws, saying that those who pose a grave risk to public safety must not have access to firearms and that if they do, those firearms can be taken through rapid due process.

boston police car
A Boston Police car is seen before game six of the 2013 World Series on October 30, 2013 in Boston, Massachusetts.
Photo by Rob Carr/Getty Images

Researchers looked at the files of gunshot victims in the Boston Police Department.

They found that the caliber of the gun played a big role in how fatal the shooting was.

Medium- caliber weapons were more likely to kill people than small caliber weapons. Those shot with large caliber weapons were more likely to die than those shot with small caliber weapons.

Replacing all guns with small ones would have reduced the rate of homicides.

Mourners take part in a vigil near the border fence between Mexico and the U.S after a mass shooting at a Walmart store in El Paso U.S. in Ciudad Juarez. August 3, 2019. REUTERS/Carlos Sanchez
Mourners take part in a vigil near the border fence between Mexico and the U.S after a mass shooting at a Walmart store in El Paso, August 3, 2019.
Carlos Sanchez/Reuters

The US has more mass shootings than any other country. Yemen has the second-highest per-capita rate of gun ownership in the world, and it is the only country with more mass shootings per capita.

Guns are easy to get in the US because of its policies. Some gun-control measures, like banning some types of weapons, improving background checks, and putting more restrictions on weapon access, could save lives.

Gathering and analyzing data can help leaders determine what changes might prevent another tragedy.

The earlier version of this story was contributed to by Kevin.

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