Residents attended a prayer vigil to remember victims of the Santa Fe High School shooting at Walter Hall Park on May 20, 2018 in League City, Texas. Scott Olson/Getty Images

Mass shootings are becoming more deadly across the US.

They're so worrisome that veteran kidnapping expert and hostage negotiator Billy Jensen has started teaching classes to churchgoers and doomsday preppers about how to prevent mass shootings, and what to do if one happens where they live, work, shop, or pray.

He emphasizes the importance of being in tune with your environment, and watching out for your neighbors.

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SALUDA, North Carolina - It's muggy and just after 9 AM on a Saturday morning when a crowd of a couple dozen doomsday preppers take their seats underneath a large white tent for an hour-long "Undercover Soccer Mom" training.

There are mothers, daughters, fathers, sons, and one journalist in this crowd at Prepper Camp - a three day long event where 1,200 people have congregated to chat about strategies for apocalyptic survival, whether the end of days arrives by hurricane, flood, civil war, or electromagnetic pulse.

Not one of these people is at the "soccer mom" training because they're interested in team sports. Instead, they're here to learn how to avert deadly disasters, and specifically, mass shootings and improvised bomb attacks.

Developing 'situational awareness' is key

Close your eyes, the two trainers standing at the front of the tent tell us.

Think back to what you ate for breakfast. What color shirt are you wearing? How many people are sitting around you? And where would you go if, right now, disaster struck and you had to take cover?

This is the "situational awareness" that the founders of a company called Captive Audience want every American to begin developing.

"If you make it part of your daily routine, you're not being paranoid," Captive Audience CEO Billy Jensen told Insider. "There are people who don't have your best interest in mind, and they will capitalize on people who aren't paying attention to their surroundings."

He said the training session we were sitting at was not really even his idea, but instead sprung up by popular demand as a new Prepper Camp course this year "because people want to know how to deal with active shooter situations."

Prepper Camp 2019. Hilary Brueck / Insider

Mass shootings are still relatively rare, but they're becoming deadlier

It's fair to say that mass shootings are still rare occurrences. Your odds of dying in a mass shooting over a lifetime are about 1 in 11,125, lower than the chances you'll die choking on food, riding a bike, or falling.

Still, in recent years, Americans have watched as the frequency and deadliness of mass shootings continues to mount.

In the absence of federal policy changes, people want to know what they should do if they're confronted with a would-be attacker.

Jensen, who said he's a former Army Special Forces Green Beret with more than a decade of experience abroad working on recovery missions for civilians and military personnel, is now bringing his expertise home.

"Every single one of the kidnappings I've worked overseas, there was surveillance that happened beforehand," he said. "There was information gathering where people were asking questions. There were strange things happening on people's social media. All of those things led up to an event."

If you smell chlorine, bitter almonds, or diesel fuel, there might be a homemade explosive nearby

The first thing to do in your everyday life, Jensen said, is to become better aware of your surroundings. This involves fine-tuning your ability to "recognize the baseline," noticing what a normal day looks, feels, and smells like where you are.

In all likelihood, you don't normally smell chlorine, bitter almonds, diesel fuel, or hydrogen peroxide. Those scents can all be sniffable clues of some homemade explosives.

"If you see someone, they've got a big backpack, it's the middle of summer, they've got bulky clothes on," Jensen said, especially if the backpack is leaking or smells like gasoline or almonds, "those are things you should pick up on."

Billy Jensen is the CEO of Captive Audience, a company that teaches skills like how to get out of restraints, as well as ways to spot someone who might be plotting a mass shooting. Hilary Brueck / Insider

Make sure your friends and neighbors are doing OK

"Recognizing the baseline" extends to checking in on the people you come in contact with everyday, and making sure they're doing alright, too. People can change their behavior for all kinds of reasons, but recognizing when people aren't quite themselves can be one way to make sure those close to you aren't withdrawing socially because they're concocting dangerous plans.

It's important to give someone your full attention when you ask how they're doing, and in the Captive Audience training, we learn to:

Turn your body towards the person you're speaking with.

Give them your full attention, and mirror their posturing.

Show that you're listening by repeating back the important things they've just said.

Ask how the person is feeling: "You seem upset" or "You seem down" are fine places to start.

There's evidence this strategy may really work to avert deadly crises. Germany implemented a similar technique in the early 2000s, training teachers and students to notice warning signs of violence in their peers after a rash of school shootings hit the country.

When Germans started noticing if others around them were writing, talking, or even drawing violent intentions or fantasies, they considered those as hallmarks of "leaking" behavior, which could suggest that an attack might be imminent. Within just seven months of starting the school program, at least 19 high-risk cases were identified across the country, and those students were offered help.

It's a strategy Jensen thinks more of us could implement.

"Most Americans don't do that," he said. "Constantly taking these mental snapshots of what normal human behavior looks like, sounds like, smells like, and feels like."

Jensen's best advice during a shooting: get down, get out

In an active shooter situation, Jensen's advice is more concrete. Hit the ground immediately, and then get to safety.

"The smartest thing to do is first get to the ground, look around, and figure out where cover is," he said.

"Cover" that can stop a bullet might be concrete or steel. Even a big pile of dirt could work, if it's thick enough.

Instead of hugging walls, put a little distance between you and any wall you're around, because bullets can strike them and travel down. And if you are going to make a run for it, make sure you're away from cover for no more than 3 to 5 seconds at a time.

"I'm up, they see me, I'm down," is the mantra Jensen uses to remember that rule.

At least a couple mothers in the audience at his training wanted to know how to protect their kids and parents if a shooting happens when they're out shopping, and the Captive Audience team demonstrated how to carry an injured body of any size (dragging the person's feet behind you, put their arms over your shoulders ,and carry them like a backpack).

Jensen and his partner also showed how to get people to move when they're panicked or frozen. One technique involves grabbing a person's bicep and putting another hand on the back of their head to lead them forward. Another tip is give short, startling commands to jolt people in to action. You could also put your hands on a person's shoulders and get them to look at you.

Jensen's training is a lot like military boot camp for what he sees as an increasingly hostile civilian world.

"Make sure that you're a conqueror," he said. "Proactive in your personal safety, and in your ability to respond to anything that life throws at you."

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