Nothing quite prepares you for just how loud the sound of a gunshot is.

When I hear the first bang, I nearly leap out of my skin. I’m sitting down, with a student facing me across a desk. A second shot comes, making me jump again, and I rise unsteadily to my feet.

Into the room strides a figure, masked and carrying a pistol low by his hip.

“WHY DID YOU FAIL ME?”

I try to talk to him, but I’m tongue-tied. I ineffectually flail around to find the right combination of words, but they elude me. "Why have you got the gun?... Let’s talk about this."

“WHY DID YOU FAIL ME?”

There’s a third crack of gunfire, and the exchange is abruptly brought to an end. The masked figure has shot the student in the chair in front of me.

I’m not in a school. I’m actually on what feels like a stage-set, with chipboard walls marking out rudimentary rooms and corridors. The masked figure is not, in fact, a homicidal teenager, but Patrick Canna, a police firearms instructor.

The gunshots were 9 millimetre blanks – though they create roughly the same sound as live rounds. And the "student" who was "shot" in front of me is Dave Zannin, a volunteer who is unscathed and quite alright. No one has been shot. No one is dead. I have just taken part in a training exercise.

'Distressing experience'

And yet, I would be lying if I said the encounter has not shaken me. It was a genuinely distressing experience.

That’s the point, explains Steve Felano, one of the training instructors. “You get exposed to 9 millimetre blanks cracking off that sound like real guns, people screaming, simulated terror. It’s called stress inoculation.”

I’m at the Defensor Inc training facility in Grand Island, New York State, USA. And I’ve just experienced one component of a bespoke programme designed to prepare teachers for school shootings.

So what has the simulation taught me? The lesson, according to my instructors, is that sometimes you can’t talk an active shooter down using verbal de-escalation techniques.

And that brings me to what makes this programme special. Defensor train teachers to carry guns in the classroom – and they train them to use them should the worst happen.

With American society dealing with the aftermath of yet another shooting yesterday in Texas, and still coming to terms with the Parkland massacre in Florida – just the latest incidents in a long and deadly line of school shootings – is it madness to arm teachers? Or it a sensible precaution that can help keep teachers and children safe?

I went to America to find out.

Arriving at Defensor, I’m warmly greeted by chief operating officer David Ditullio, a former member of the armed forces with 23 years’ experience in the navy and army and a deployment to Afghanistan under his belt. He’s a friendly man, but evidently extremely tough. Later in my visit, when we get on to the subject of gun control, he casually remarks: “I could break someone’s neck with my hands. You gonna ban hands?” It is clear to me that he is not exaggerating for dramatic effect.

Defensor was the brainchild of Canna and Ditullio. Occupying half of a large warehouse on Grand Island, upstate New York, the company instructs civilians in gun ownership and self-defence. The idea was to prepare people to deal with a potential attacker in the most realistic way possible.

“Right now a lot of people train on paper targets,” Ditullio explains. “Until you’ve actually looked at someone who’s trying to kill you, coming at you like that, you really aren’t prepared.”

The scourge of school shootings in America meant it wasn’t long before they were seeking to apply their techniques to a classroom environment. It might seem almost unbelievable to a British audience, but under New York State law, teachers are already allowed to take a concealed weapon into work with them, so long as they have a concealed carry permit and the authorisation of the local school board.

Saving lives in a school shooting

Next I meet Felano, Defensor’s director of partnerships. An articulate young man with a seemingly inexhaustible supply of knowledge about firearms and the US gun debate, he differs from Canna and Ditullio in not having a law enforcement or military background – his day job is in marketing.

Although he came from a gun-owning family, Felano’s serious interest in firearms was provoked by an incident he experienced while a university student. Jumped by a group of men while walking in a relatively affluent area, a gang member pressed the barrel of a gun against the back of his skull and pulled the trigger. He’s only alive today because the pistol was poorly maintained and malfunctioned. He applied for his concealed carry permit shortly after.

According to Felano, the movement to arm teachers in America really took off after Sandy Hook, the bloodiest school shooting in US history, when 20 primary-age children and six adults were killed. But the sheer frequency of school shootings means the movement has been growing in momentum ever since – so far in 2018 there have already been at least 20 shootings in which someone was hurt or killed at educational institutions.

Defensor delivers a programme originally developed in Ohio, which has to date trained 1,300 educators across 12 states and over 200 school districts. Another 800 teachers are due to pass through the programme this summer.

“Schools want answers,” says Ditullio. “They just know that they want this to stop. A lot of schools have taken an unarmed approach, and we still saw a deadly result.”

While training teachers to use a gun is a key part of Defensor’s training, the organisation is at pains to point out that it’s not the be all and end all. Felano says that 85 per cent of the programme doesn’t actually involve a firearm at all. Instead, it’s about training teachers to be “full spectrum first responders to an active killer event”.

“We teach people that the world is not nails, and we’re not only giving you a hammer,” he says. “Meaning that not everything can and should be solved with a firearm.”

So what are the none gun-related elements of the training? The first is situational awareness – identifying someone who may have ill intent before they have the chance to strike.

Ditullio now works as a behaviour detection officer at airports and train stations, looking out for individuals like would-be suicide bombers. People with ill intent usually carry out surveillance to plan their attack, he says, so potential giveaways could be a pupil asking questions about security measures, writing notes about the school environment or taking panoramic pictures. He trains teachers to construct an “environmental baseline” – to ask themselves “what’s normal for this environment” and then to look for things which stand out as unusual. “Saved my life three times in Afghanistan,” he adds.

People who are planning to do something awful – or who have just done it – are under immense stress, which also creates tell-tale signs. “These behaviours are released or leaked from your body, either physiologically or physically,” Ditullio says. “What I’m looking for is that leakage… that could be anything from sweaty palms, excessive perspiration, an obvious Adam’s apple gulp, hesitation and indecision.”

For when an individual has been identified as potentially suspicious, Ditullio gives teachers techniques to tease more information out of them. They should mainly aim to ask “open-ended” rather than “closed-ended questions” – so not questions which can be answered with a yes or a no. “Someone who has ill intent has a certain idea of what kind of questions they’re going to be asked, and they pre-plan those in their head,” he explains. “Through the right questioning, you can break beyond that layer.”

If it turns out the person is armed and their intention is malign, the next stage is to try to resolve the situation without using lethal force. “We talk about how do you de-escalate that situation, how do you use your body language, how far do you separate yourself from a person,” says Ditullio. Teachers should give the impression they empathise with the person. “Say, 'Look, man, I know where you’re coming from’ – even if you don’t, even if you don’t believe in what they’re saying. They could tell me the sky is green and I’m going to go, ‘Yes, I agree, and I don’t know why these people don’t understand that, but you’re 100 per cent correct, and what can we do, what are you looking for?’”

Those on the programme are taught pressure-point techniques to disarm people non-lethally. But if none of the other interventions have worked and a gunman is on the rampage, teachers are trained to go for the “last and worst option”.

“We have an option as opposed to sitting there and dying until law enforcement can arrive,” Ditullio says grimly.

This is where the life-like simulations come into play. Using the mock-building which Defensor has rigged up, teachers are drilled on how to take on armed killers. The assailant is equipped with a gun firing blanks, while the teachers are given gas blowback training pistols which fire pellets.

Dave Zannin, a softly spoken man who worships at a church with educational provision, has passed through the programme. After seeing religious and educational institutions repeatedly targeted by gunmen, his church decided to put a team through the training. “Is it probable that it’s going to happen here?” he asks. “No, the probability is very slim. But it doesn’t mean it isn’t possible.”

Although he’s an ex-military man himself, he says little compares to the level of stress you experience during the scenarios. On one occasion the experience felt so terrifying real, he says, his heart was beating so fast he feared he was physically going to pass out. But he believes it’s necessary to go through this ordeal. “If you train and practice enough… when it hits the fan, your body is going to do what it has done hundreds if not thousands of times, despite the stress. The training here is invaluable.”

The final bit of the training focuses on coping with the aftermath of a shooting by tending to the wounded and “de-conflicting” law enforcement – ensuring that gun-wielding teachers are not mistaken for the shooter when a SWAT team arrives.

Trainees are taught "TCCC" – tactical combat casualty care. Following a shooting, most people are not killed by bullet impact, but by blood loss before emergency services can get on the scene, so teachers are taught how to apply chest seals and how to fashion tourniquets out of belts and shoelaces. Referencing last October’s mass shooting in Las Vegas, in which 58 people were killed, Ditullio says: “Had these skills been applied before help arrived, then probably half of them or more would have been saved.”

It’s not difficult to find people who believe that the armed teacher element of Defensor’s training is completely wrong-headed. “Universally, people who work in the educational sector find the idea absurd,” says Dana Goldstein, education correspondent for The New York Times.

Teachers 'are against carrying guns'

“There are a few schools and teachers that are interested in teachers handling guns, but the vast majority of teachers and principals who I have asked about this almost laugh; they find it so completely ridiculous.”

Goldstein thinks that the reason people are discussing the idea now can be explained in two words: Donald Trump. On 24 February, the president tweeted: “Armed Educators (and trusted people who work within a school) love our students and will protect them. Very smart people. Must be firearms adept and have annual training.”

“I truly think that the only reason anyone is talking about arming teachers is because of what President Trump tweeted,” says Goldstein. She points out that every time there is a school shooting in the US (“sadly frequent in our country”), the National Rifle Association gun-lobbying group calls for teachers to be armed. “Never before was this amplified to the level of a presidential pronouncement,” she points out.

Some of the fiercest critics of teachers carrying guns are the very young people who they would supposedly be protecting. Kevin Trejos, 18, is a student from Marjory Stoneman Douglas High School in Parkland, Florida. When the school was attacked on Valentine’s Day, he hid in a closet for several hours before police arrived and told him to flee.

Trejos helped organise the March For Our Lives protest, in which thousands of people descended on Washington DC and many other cities across the world calling for tighter gun control. “I don’t agree with arming teachers, especially teachers who have students full time,” he tells Tes. “It would cause more problems that it would fix.”

He says that knowing a teacher had a firearm would make people “uneasy” and could put pupils at risk. “Teachers are just like anyone else. Some of them have their own mental health issues. I love teachers, but they’re not all perfect.”

Trejos estimates that about 60 per cent of his classmates are “completely opposed” to any school staff being armed. A “decent amount” – himself included – would be more comfortable with security officials, administrators and part-time coaches carrying guns. But Trejos says that some of his fellow students do support giving teachers weapons. “There are people who say we should arm all teachers, or arm whatever teacher wants to be armed, because they think that a gun protects people,” he says.

For its own part, Defensor claims that the case that is made against it is based on misconceptions. Ditullio says: “The misunderstanding is that a lot of people think that we just go into a school and say: ‘Math teacher? History teacher? Spanish teacher?’." As he names each one, he mimes the action of dolling out a gun. “That couldn’t be further from the truth.” Only those who want to be armed and who have passed the requisite training should carry guns, he says.

For Defensor to recommend to a school district that a teacher should be authorised to carry, the candidate needs to score 93 per cent or higher accuracy in a marksmanship test – a standard which the company says is higher than the test which police patrol officers need to pass.

But rather than arming teachers, wouldn't stricter gun control be a more effective way of stopping school shootings? “Our founding fathers developed a constitutional inalienable right to defend ourselves,” says Ditullio firmly. “I don’t think we’ll ever see a time when the US says no to weapons, because I think if that happens, you’ll see a civil war.” He says that blaming guns for mass shootings is like “blaming the pencil for misspelling words”, and refers to “very vivid video games” warping children’s minds. If you outlawed guns, he insists, people would just find other ways to kill each other. “If you take that away from me, I’ll get barbaric with a sword. I’ll use cow manure to blow a building up. People are crazy.”

When it's pointed out that the UK, with its much tighter laws, has only seen one school massacre in its recent history – Dunblane in 1996 – Felano chips in. “There are severe cultural differences between England and America. America is a more violent country,” he says. “I’m not going to try to sugar-coat that or dance around it.” He thinks poverty, “massive inequality” and the crisis of addiction to opioid painkillers have created conditions in the US “that put stress on people to the point where they pop and break”.

Even those who are opposed to teachers being armed seem to accept the impossibility of America giving up its guns. Asked whether the US should introduce sweeping UK-style gun laws, Trejos says: “In an idealistic world I think that could be a solution. But the way that culture and politics is in the US, I think that’s impossible, so there’s really no point advocating for it.” Instead, the March For Our Lives campaign is focused on more incremental gun control reforms.

One of the things that's difficult to avoid in America is how appallingly normal and quotidian school shootings have become. It is summed up most perfectly by a recollection from Trejos about the Parkland attack. Hiding inside the closet with his classmates, and watching on a phone the live stream from one of the helicopters circling the building above him, the surreal familiarity of the situation hit home.

“We grew up in the age of school shootings,” he reflects. “I was literally at the school, during the school shooting and I was just like, ‘Oh, it’s just a school shooting’… It was like we didn’t think it could happen to us, but we’re not surprised it’s happening."

Will Hazell is a London-based reporter for TES magazine