Each major school shooting—Columbine, Sandy Hook, Parkland—has helped expand a multi-billion dollar industry that sells not just sophisticated surveillance technology, but also high-priced consultants to explain it all to anxious educators. The recent tragedies are providing momentum—not to mention funds, including millions of dollars in federal money—to initiatives that aim to keep children safe. As the tragedies have piled up, some education leaders say they’re inundated with sales pitches from security companies, each with the same basic message: You could be next.

Such a climate is “ripe for exploitation,” argues Kenneth Trump (no relation to Donald), the president of National School Safety and Security Services, which consults for districts on school-safety planning. The result, according to Trump, is that the security industry has dominated the policy response to school shootings, drowning out subtler conversations about issues ranging from mental health to gun control, in favor of a rush to adopt costly, and largely unproven, methods to harden schools. “It’s not that they’re villains and they don’t care and they don’t want safe schools—I’m not trying to send that message,” said Trump. “But they’re certainly opportunistic. At the end of the day, they’re looking for new revenue streams.”

The security industry’s spectacular growth began with Columbine. Before that, Guy Grace said security efforts in his Colorado school district focused on kids with cans of spray paint, not guns. Grace, the director of security and emergency preparedness at Littleton Public Schools, says the shift he witnessed was instantaneous.

On the morning of April 20, 1999, he was at the gym when his pager went off. Two students had walked into Columbine High School, in a neighboring school district, and killed 15 people, including themselves. After that, his job was never the same. “It was a complete change, just a wake-up call for us all,” he said. “It certainly has shaped a lot of what we do across the country in regards to school safety.”

Before Columbine, Littleton didn’t have any security cameras at its schools, Grace said. The district has since installed more than a thousand cameras, some with analytics capabilities that can alert authorities to unusual activity, such as someone walking onto school grounds in the middle of the night. The cameras are one part of the school-security regime the district implemented after the community approved a bond in 2013 providing more than $7.5 million for the upgrades. Just last year, Grace said that a gunshot-detection sensor, which can recognize the audio signatures of gunfire, alerted officials when a student committed suicide on a school playground.