Parents, administrators and politicians across the country are discussing what to do to keep schools safe from violence following the shooting inside a South Florida high school that left 17 people dead.

A start-up that's developed a bulletproof structure for classrooms believes it can save students lives in the next school shooting. The customizable steel enclosures built by Shelter-in-Place are outfitted with panoramic view cameras, a circulation system and backup power. They are used in two school districts in Oklahoma, Healdton and Atoka, to protect from tornadoes.

"I believe in being prepared for the storm before it comes before a literal threat. What we are facing nationally now with active shooter shootings - being prepared saves lives," said Kayse Smith, a veteran of two tours in Iraq and mother to a preschool boy at Healdton's elementary school.

"It restores my faith in mankind that people ... put forth time and resources to make those shelters," she added, "that they care that much about our children."

Jim Haslem, owner of the Utah-based company behind the structures, says they can prevent student deaths from violence and natural disasters at schools, limiting danger to the police who try to stop the gunman.

"It's a great deterrent. If the shelters are there in schools, violence will be just be a shootout between the shooter and police," Haslem said. "If you have a heart, you need to protect kids."

The debate over how best to stop school shootings has raged for two weeks, since a 19-year-old former student allegedly killed 17 people, many of them students, at Marjory Stoneman Douglas High School in Parkland, Florida.

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President Donald Trump has proposed arming some teachers and "hardening," or fortifying, schools against gunfire, while many students from the school are calling on politicians to pass stricter gun laws.

Every Town for Gun Safety, a nonprofit group co-founded by Michael Bloomberg, tracks school shootings. Since 2013, the group reports, there have been 291 school shootings in the United States. The Washington Post notes Every Town’s definition of school shooting is inclusive of all shootings on school property, regardless of student involvement or accident. The exact number of school shootings where students were involved may be lower.

One shooting is one too many, according to Andrew Pollack, a father who lost his daughter Meadow in the Douglas shooting.

"Fix it," Pollack told Trump at a White House listening session.

"It should've been one school shooting, and we should've fixed it. I'm pissed."

The Shelter-in-Place isn't the only device invented to mitigate school shootings, which have become a persistent fear in modern American education. A Washington, D.C., student created an emergency door-lock device in 2013, after the Sandy Hook Elementary School shooting. A Wisconsin high school student recently created a door jam latch that prevents classroom doors from opening.

The Shelter-in-Place is much larger -- and costlier -- and also can withstand tornado- and hurricane-force winds, as well as bullets, according to Haslem. He said that, in 2012, he and his wife watched the news coverage of the Sandy Hook shooting and the Moore, Oklahoma, tornado that killed seven children, and figured someone had to do something.

"With all the people we know, we knew we could create a solution to shootings and structurally engineer safe rooms," he said.

But it was tornadoes that prompted the first schools to get the Shelter-in-Place units three years ago. They are a daily concern in Healdton, Oklahoma, during the spring.

Terry Shaw, superintendent of the Healdton Public School, said he had checked into superstructures like the ones the Federal Emergency Management Agency helps schools build, but they were too costly to get a bond passed for his tiny district of about 500 students.

So he turned to Shelter-in-Place after Dani Legg, a former Healdton student, introduced him to Haslem in 2014. Legg lost her son Christopher in the tornado that hit the school in Moore.

Children "need to feel safe in school, where they can learn, make friends, be a child and not worry about the building collapsing," she said.

President Trump held an hour-long bipartisan discussion to address gun control and other measures that lawmakers can take to prevent mass shootings.

Shaw acquired a bond to pay for six of the bulletproof shelters, which he said cost about $30,000 per unit. He ran the Oklahoma City Marathon and received donations to cover the cost for the seventh structure. Five are placed in Healdton's elementary school and two are in the middle school. Shaw hopes to acquire more shelters for the middle and high school as he sees the dual purpose of the unit protecting his students from natural disasters or a mass shooting.

"We are glad to have them, but hope to never have to use them," Shaw said. "The sense of security that [a shelter] gives you is kind of hard to explain. We are going to save lives with this.

Because Healdton has not needed to use the shelters for an event, the school has turned the bulletproof structures into learning centers in the back of the classroom. The elementary school structure, he described, is about 8 feet by 8 feet and has become an extension of the classroom with bench seating and carpeting. Teachers use them for quiet time and learning every day.

Haslem said they can be integrated into the class as a learning lab, and that some teachers call them tiki huts or kid caves.

He sees these shelters in every school across America, and believes it will take the government's help. Right now, Shelter-in-Place is working on contracts with about 25 schools, and offers them the option of leasing or buying the structures.

Prices depend on the price of steel, but Haslem estimates the structure costs about $1,000 per student -- for a classroom of 25 students and a teacher, it could run $25,000 to $30,000.

Melissa Hudson, president of the Healdton Parent Teacher Association, agrees with the investment, and says her son uses the bulletproof shelter as a place to read.

“As a parent of a 5th grader & 8th grader, when I drop them off in the morning, no matter what might happen during the day at school, I have the security knowing that they have a secure shelter to go to. I know exactly where they are and they are safe. This is priceless!!!”