One hundred and forty minutes. That’s the amount of time between when gunmen at the Bataclan theater began rounding up survivor-hostages after their initial killing spree, and when police began their successful assault on the theater. All told, it was over 160 minutes from the first shots to when the first responders were able to reach those inside the venue: more than two and a half hours.

ISIS’s attacks in Paris offer an extreme example of a general principle of active-shooter attacks: Even the best emergency personnel cannot reach shooting victims until the threat has been neutralized. For a period of time that is very often going to be longer than it would take someone with a serious wound to bleed out, the victims are on their own.

This vulnerability is, in part, what motivates some to call for arming citizens for self-defense. Whether or not giving every Parisian a Glock, as Donald Trump might like, would be either practical or effective is unclear; leaving aside any unwanted side effects of increased gun ownership, one needs at a bare minimum to go through an awful lot of practice ammunition at the range and be carrying the gun at all times to be of much help in a shooting. But even supposing every terrorist attack was met by a civilian-led shootout, that still wouldn’t solve the problem presented by a victim shot in the thigh, dying on the floor. Whether professionals or amateurs are involved, taking down multiple shooters can take time. Active-shooter incidents present both a security and a medical challenge.

This is an entirely foreign scenario for most people, which adds an extra element of terror. But it’s also a scenario one segment of the population is uniquely familiar with: the military. And in recent years, a number of doctors have become convinced that the lessons learned in battles abroad could also be used to protect people at home: In mass shootings and terror attacks, perhaps civilians could be their own first responders.

On the Saturday morning after the attacks in Paris, students in a martial-arts studio I attend in Boston settled down for a three-hour workshop in tactical first aid for civilians, led by David Schaffner, a former U.S. Army medic who served in Iraq and Afghanistan. The timing of the workshop was a coincidence, but it caused Schaffner to grimace and speed through his PowerPoint slides outlining the usefulness of these skills. “I don’t think I really have to explain the relevance to anyone after last night,” he said.

Tactical first aid for civilians, he explained, is an adaptation of what the U.S. military calls Tactical Combat Casualty Care (TCCC)—a response to the realization that soldiers were dying on the battlefield from survivable wounds before they could make it to a hospital. A 2012 study found that almost a quarter of deaths in the wars in Iraq and Afghanistan were “potentially survivable,” and 90 percent of deaths overall occurred before the casualty could be treated at a medical center. Numbers like those, including a statistic that 90 percent of those with potentially survivable wounds died specifically from “uncontrolled blood loss,” have recently led both the military and civilian groups to focus on techniques that can be performed quickly with minimal training by non-medical personnel, in the hope that future deaths might be avoided.

Tactical Combat Casualty Care involves not just medical techniques, but threat recognition and situational awareness. The 1996 paper by members of the Army and Navy medical corps that established the TCCC guidelines divided care into three stages: 1) “care under fire”; 2) “tactical field care,” or “the care rendered by the medic or corpsman once he and the casualty are no longer under effective hostile fire” but have not yet been picked up for transportation to a medical center; and 3) “combat casualty evacuation care” once in a vehicle en route to a medical center.

The main concern during “care under fire,” as explained by Schaffner, is not actual medical attention but “handling the immediate situation”; in other words, moving oneself, and the wounded person, to a safer area. The only medical intervention at this stage would be, if possible, to stop major bleeding from an extremity wound with a tourniquet—a compression device placed on the limb above the wound. (Although tourniquets are now judged to be safer than previously thought, those wishing to provide first aid should always seek out instruction from a professional, and be aware of local laws governing the provision of first aid in emergency situations.)

The majority of tactical field care takes place once you have moved, the shooter has moved, or some sort of new barrier exists between you and the threat. The emphasis on recognizing when the situation has changed is part of what makes such care a response not just to the medical aspect of shootings, but the security aspect as well.

The idea that these techniques could be transferred from the military to the civilian sphere has gained momentum in the United States since the 2012 slaughter of 20 schoolchildren and six adults in Newtown, Connecticut, according to E. Reed Smith, the co-chairman of the Committee for Tactical Emergency Casualty Care (C-TECC), a volunteer organization composed of civilian and military medical experts. Four months after the Newtown shooting, the American College of Surgeons founded the Joint Committee to Create a National Policy to Enhance Survivability from Intentional Mass-Casualty and Active Shooter Events. The result has been a series of conferences producing what has become known as the Hartford Consensus: a collection of recommendations centered on the principle that “no one should die from uncontrolled bleeding.” In a July article in the Bulletin of the American College of Surgeons, the Joint Committee argued that “bystanders” should instead be thought of as “immediate responders,” and that first-aid courses should include lessons on how to properly apply tourniquets. The same principles underlie the White House’s “Stop the Bleed” campaign, launched in early October.

At the Saturday morning workshop, Schaffner moved from tourniquet instruction to pressure dressings—to be applied after a tourniquet is in place, if the bleeding is not bad enough to require a tourniquet, or if the wound is in a location where using a tourniquet isn’t possible (anywhere not on the arms or legs). From there, it was on to addressing compromised airways by moving the patient into a better position or, in the case of a chest wound, buying time with what’s known as an “occlusive dressing”—an air-tight bandage that helps keep air from being sucked into the chest cavity, and displacing and deforming the lungs and heart. Then came the very few things—mostly involving positioning—that non-professionals can do to slow the onset of shock or delay swelling for bad head injuries. For the remaining two hours, participants practiced putting tourniquets and pressure dressings on each other—applications that can be quite painful for the patient, when done properly. Schaffner circulated, sliding a finger under a dressing or onto a pulse point to check for sufficient compression. Almost always, the tourniquet needed to be tighter. Then he timed the students. Finally came a few maneuvers for quickly moving the injured out of harm’s way.

When I recounted this curriculum to C-TECC’s Smith, he was pleased. Smith, a physician specializing in emergency care, supports training civilians in military techniques to improve survival, but he argues that the attacks in Paris demonstrated why those techniques need to go beyond methods to control bleeding.

“If I shoot you with a bullet in Paris,” said Smith, “the damage to your body is the same as if you get shot in [the Iraqi city of] Fallujah. However, the pattern of injury is different. Nobody who was shot or blown up [on Friday] in Paris had ballistic armor on.” That means a lot of close-range shots taken to the head or chest, rather than to extremities where tourniquets would have been helpful. As the Parisian physician Patrick Pelloux told The Guardian after tending to the wounded: “Most [of the shots] were aimed to kill, at the head, thorax, abdomen.” A similar situation occurred in Newtown. “None of the 26 people in Newtown had a survivable injury,” Smith said. “There’s nothing we could do in Newtown.”

The different pattern of injuries in civilian populations, combined with the fact that civilian populations do not resemble the “18-to-40-year-old healthy, deployable military population” off of which all military research is based, make Smith skeptical of attempts to transfer the military’s emphasis on tourniquets to civilians. “It’s a great starting point,” he said, but “let’s move on to how to safely move a patient, how to position them, how to interact with 911, because most people in a panic don’t give us the right information. Let’s talk about improving breathing for people who have been shot in the chest or abdomen. Let’s talk about keeping them warm. Let’s talk about knowing how to recognize truly severe injuries.”

When it comes to tactical first aid, it’s unlikely that civilians can achieve quite the same improvements in survivability that the military can. C-TECC’s attempts to collect autopsy data from U.S. mass shootings between 1966 and 2012 suggest that between the lack of body armor and the closer range of the shooter in civilian situations, fewer civilian injuries are survivable relative to those on the battlefield (the resulting paper will be published in January).

But that doesn’t mean training the civilian population in such care won’t have an effect. “No one’s ever done a randomized controlled trial that says parachutes will keep you from dying,” offered Smith by way of analogy. But using parachutes is probably a good idea when jumping out of a plane. So is knowing how to deal with a chest wound in an era of mass shootings.

A less quantifiable benefit of learning tactical first aid is empowerment. “Intuitively yes, I think we’ll save lives,” said Smith, in reference to more civilian training. But additionally, “it improves resiliency in the community, and decreases psychological damage” when ordinary citizens have a plan in case of emergency, and don’t feel powerless in the face of unpredictable threats.

If empowerment on its own seems insignificant, consider that decisive action and situational awareness—both facilitated by tactical care training—are considered by many psychologists and self-defense experts to be some of the most crucial factors in surviving an emergency situation.

Then, too, consider the vigils, the Facebook postings, the flowers outside embassies since the Paris attacks: visible signs of a search for the right way to express solidarity, and to indicate resistance rather than fear.

What might happen if these impulses were converted into practical action—if people were to present themselves en masse for tactical first-aid training? (After all, ISIS issued another round of threats this week.) What difference might it make if pressure-dressing practice became the global version of the American flag outside the door after 9/11? If the enduring image of the Paris attacks became that of citizens the world over practicing body positioning and carrying techniques? It’s hard to think of a response that would better unite the sentimental and practical instincts on display since Friday.

“We were very scared,” said a French doctor interviewed by Channel 4 in the U.K., upon surviving one of the restaurant attacks in Paris. After the shooting stopped, “There was no cop, no firemen whatsoever. We were just alone.” That will likely happen in a shooting no matter what. But in the absence of professional help, there can still be a plan.