A 6th grader was killed and Grant Prestonfive others were injured in a shooting at Perry High School in Perry, Iowa, on Thursday. 

American schools are expected to spend $3.5 billion on security this year, according to the research firm Omdia, part of a growing trend in spending on defense against active shooters.

Greg Vecchi, director of research and training at SafeDefend, says the company's technology can help people survive a shooting at schools and workplaces.

"Think of it as the fire alarm for active killers," he told CBS News.

In 2014, a gunman opened fire in the parking lot of a Jewish Community Center in Overland Park, Kansas, killing a man, his grandson and a third person who was nearby.

"To come in the building and see bullet holes, glass shattered, definitely an immediate loss of security," said Sandra Greason, an employee at the center.

Since then, the center has installed license plate readers, more cameras, armed guards, metal detectors, and now, SafeDefend devices.

The technology was created by Jeff Green, who left his job as an elementary school principal to work on it.

"No matter how much law enforcement wants to be there, there's a gap," Green said. "There's a time when we're on our own. And how do we survive until help arrives?"

Greason told CBS the center's new safety measures, which also include active shooter training, make her feel more secure. 

"Preparedness is key, right? The more you're prepared, the better you feel and the more confident you feel," she said.

SafeDefend is just one part of what's become a booming industry aimed at protecting kids and employees from a rapid rise in mass shootings. Products range from gun detectors guided by artificial intelligence to bulletproof tables and automatically locking doors.

Odis Johnson Jr., executive director at Johns Hopkins Center for Safe and Healthy Schools, is skeptical these products are the answer to gun violence.

"We've seen year-over-year increases in death and injury," he said.

"We really do need a more comprehensive approach that includes gun safety and stiffer regulations for gun ownership," Johnson added.