Law enforcement experts are asking people to consider this question so that they will be prepared to act rather than freeze if the unthinkable happens. Here are the basics of the "Run, Hide, Fight" program created by the Department of Homeland Security. (The Washington Post)

The mass shootings that have terrorized America have led to a new focus on how to survive them. Though far from an exact science, these efforts are based on a disturbing amount of data – including case studies, the body counts from these tragedies and the personal narratives of people who somehow got out alive.

A number of private companies now train office workers in how to respond in an active-shooter event. The experts agree: Following a few simple rules can help boost a person’s chance of survival. Being mentally prepared to take action in a crisis — or simply knowing where a building’s exits are — can make the difference.

The massacre at the Pulse nightclub in Orlando early Sunday fits with the general, horrifying pattern in recent years, in that life and death pivoted to a large degree on how the people there reacted in the initial minutes. Research shows that it usually takes about three minutes for police to arrive at an active-shooter situation — although the Orlando club had an extra-duty uniformed police officer working security, and he engaged the shooter.

The best move for civilians, as always, was to get out of the place immediately by any possible route. Many escaped through rear and side doors onto a patio. Less fortunate were those who went into the restrooms, a dead end, and became trapped when the gunman came in after them.

“When you go somewhere, you don’t want to put yourself in a situation where if you get found, you don’t have any options,” said J. Pete Blair, executive director of the Advanced Law Enforcement Rapid Response Training Center, based at Texas State University.

Blair co-authored “Active Shooter: Events and Response,” which includes guidance for civilians. The book’s mantra is “Avoid, Deny and Defend.”

The Department of Homeland Security has endorsed a similar concept, built around the words “Run, Hide, Fight.” The latter option gained attention after D.C. Police Chief Cathy Lanier said on “60 Minutes” last year that people should be prepared to take out an attacker before the police arrive.

Blair said that kind of action is really a last resort: “When we do our training, we always stress that it’s ‘avoid, deny, defend,’ and they’re in that order for a reason.” He said he’s not entirely comfortable with the “hide” concept; killers can find people under a desk, for example.

“Hide is a passive action. As opposed to ‘deny,’ where I try to keep you from getting to me,” Blair said.

The more active response is to barricade a door, or ideally lock it; his organization does not know of a case in which an active shooter breached a locked door.

He also cautioned against playing dead as a strategy: Although news reports have suggested that some of the Orlando victims survived by pretending they were dead, that often has not worked, Blair said.

“When you play dead, we see time and time again in these situations the shooters continue to shoot people who are down and who they think are dead,” Blair said.

Blair’s book warns against people with concealed handguns trying to engage a killer except as a last resort:

“The last thing you want to do in an active shooter event is to pull your gun out and go hunting for the shooter. If there are other concealed gun carriers in the attack location, they may shoot you. If the police show up and you are running around with a gun, they will probably shoot you. Remember that no one knows who you are. The responders are looking for someone with a gun and you match that description.”

Research on active-shooter events, as well as other mass-casualty incidents, including the terrorist attacks of Sept. 11, 2001, reveals the many mental and physical challenges that arise when a person is suddenly plunged into an unfamiliar, unexpected, and terrifying situation. Very few people have ever experienced anything like this. As a result, most people are slow to grasp that something terrible is happening. In the Pulse nightclub, for example, people heard the initial gunfire from the shooter, Omar Mateen, but many assumed it was firecrackers or part of the music.

In a crisis in a confined space, people often instinctively behave in ways that do not boost their survival chances. For example, people typically try to leave a building through a main entrance rather than a secondary exit. That can create a bottleneck.

Two survivors from the 2007 Virginia Tech shooting share their story of coping in the aftermath of a tragedy and how it still impacts them to this day. (Alice Li/The Washington Post)

The classic example, involving a fire and not an active shooter, happened in the Station nightclub in West Warwick, R.I., on Feb. 20, 2003. A heavy metal band’s pyrotechnic display led to a fire in the wood-frame club. At first people thought it was part of the show. The fire spread rapidly and people stampeded toward the main entrance, where firefighters later found 25 bodies. A hundred people died in the fire.

That leads to one obvious tip to increase your chances of survival: Know your secondary exits. As a routine matter, people should understand how to get out of a building through emergency exits or back doors in case some event takes place that demands speedy evacuation. All buildings have these exits – they’re required by fire codes.The point of fire drills is to train the mind to know where to go, without having to ponder the issue, in a situation that might be confusing and when people might not be thinking clearly.

A building may have more exits than people realize at first glance. Consider the case of a food court: There may be only a couple of primary entrances and exits, but the food vendors probably have their own exits, via their kitchens. If trapped in a food court, Blair said, he’d jump a counter and flee through a kitchen.

Research suggests that there is little hope of reasoning with a mass killer, Blair said. The better move, if there’s no way to flee or find protective cover, is for multiple people to swarm the attacker. They should use whatever they have at hand as a weapon — coffee cups, car keys, anything.

“In general, this person has already shown a desire to murder people. To murder a lot of people,” Blair said. “Is there a chance you might be able to talk him down? There might be a chance. That chance is probably small. We just don’t see it happen in these cases. But we do know that in about 1 out of 5 cases we’ve seen people successfully stop the attacker.”

Read more:

When active-shooter event became hostage situation, police made tough call

When active-shooter event became hostage situation, police made tough call

After a mass shooting, a survivor’s life

The memory of a mass shooting can haunt survivors for years

Infographic: Mass shootings in America