Students at the University of Toledo learn to confront an active shooter and master other survival techniques during a session by the ALICE Training Institute. (University of Toledo Police Dept.)

A day after the terrorist attack in San Bernardino, Calif., left 14 people dead, Temony McNeil was on the floor of his Washington office, pinned down by co-workers.

At 6 feet and 240 pounds, McNeil is no pushover. But when colleagues being trained to take down an active shooter got control of his neck — he’d need Advil afterward — the senior accounting manager found himself unable to go anywhere.

“They had me down,” he said.

McNeil, 39, had been tapped to impersonate an active shooter in the role-playing exercise. With guidance from a former SWAT team officer, his co-workers at NeighborWorks America, an affordable-housing group based in the District, were rehearsing their response — going after their predator, not cowering behind a desk or hiding in the corner.

From Silicon Valley tech companies to Northern Virginia credit unions, this new approach to the threat of active shooters is gaining ground.

Students at the University of Toledo are taught how to swarm and disrupt a gunman during a training session by the ALICE Training Institute. (N/A/University of Toledo Police Dept.)

Spooked by a year of high-profile rampages, hundreds of companies and organizations like NeighborWorks are racing to train their workers how to react to a shooter in their workplaces. And after decades of telling employees to lock down and shelter in place, they are teaching them to fight back if evacuating is not an option.

The idea: Work as a team to disrupt and confuse shooters, opening up a split second to take them down.

The paradigm shift in response — from passive to active — has been endorsed and promoted by the Department of Homeland Security. Last month, it recommended that federal workplaces adopt the training program “Run, Hide, Fight,” which it helped develop. D.C. Police Chief Cathy L. Lanier used the same phrase on a recent episode of “60 Minutes.”

“Your options are run, hide or fight,” Lanier said last month. “I always say, if you can get out, getting out’s your first option, your best option. If you’re in a position to try and take the gunman down, to take the gunman out, it’s the best option for saving lives before police can get there.”

Gun rights proponents have a much different view of what works. They say that if more law-abiding citizens were armed, more mass shootings could be prevented. But most employers ban guns from the workplace, even in states that embrace concealed-carry permits.

At NeighborWorks, almost three dozen employees were taught to throw things at a shooter — chairs, books, purses, pens, phones, anything — and swarm. Those items don’t seem all that threatening compared with an AR-15, but that’s not the point.

“If you can move him from offense to defense, you have changed the outcome of the event,” said Greg Crane, a former SWAT officer whose company, the ALICE Training Institute, trained workers at NeighborWorks as well as at Facebook and Apple. “He’s thinking about what you are doing to him, not what he’s doing to you. Mentally, he’s going through a whole different process.”

University of Toledo students quickly build a barricade during an active shooter training session. (N/A/University of Toledo Police Dept.)

ALICE, based near Cleveland, has been teaching these methods since about 2001. But in the past few years, as mass shootings have killed moviegoers, congressional constituents, first-graders, Navy Yard workers, TV journalists and college students, hundreds of competitors have sprung up, charging thousands of dollars for classroom lectures and intense simulations.

Some, like the Crisis Consultant Group in Richmond, are run by Iraq War veterans. Others, including K17 Security in Rockville, Md., are run by current or former police officers. They buy Google ads connected to “active shooter training” searches and have a lively presence on social media, offering instant updates on mass shootings and advice on what to do.

After each active shooter event, demand for training spikes. ALICE executives said they received hundreds of requests for new training or refresher courses for previous clients after the San Bernardino shooting. The company held a two-day training session this month at Northwest Federal Credit Union, which serves CIA employees.

K17 Security has had a flood of new business, too. Scott Zimmerman, a police officer who runs the company, said security spending tends to be reactive.

“The worst thing in the world happens, and that’s when we’re busier than ever,” Zimmerman said. “We’ve had more requests for this kind of training over the last year-and-a-half than I can ever remember.”

For many people, the idea of confronting a mass shooter is new and totally startling. But Lanier and security professionals say they are pushing that response for a couple of reasons. For one, it works. An FBI study of active shooter events from 2000 to 2013 found that 13 percent of the incidents were stopped “after unarmed citizens safely and successfully restrained the shooter.” The other reason: With most shooting rampages ending before police arrive, what other option is there?

“If you’re passive in the face of extreme violence,” Crane said, “you’re going to get hurt.”

The training companies aren’t teaching fighting as the centerpiece of an active shooter response. Getting out — not locking down — is the first option. (Many of the students killed at Columbine High School in 1999 were hiding in the library.)

Barricading in a room is another option. ALICE and others show workers how to stack chairs, desks and other office items in front of doors, and then use belts and computer cords to secure hinges and doorknobs.

But in many cases, those options won’t work, and battling back becomes the last best hope. To convince workers that’s their best option, Zimmerman runs a simulation with a shooter entering a room and workers instructed to respond the way their brain is essentially programmed — to hide from danger, ducking behind desks or tables.

“How did that feel?” Zimmerman asks. “Was that fun?”

The answer is usually no.

“Everyone thinks it’s awful and miserable. And it is,” he said. “They are just sitting ducks. They are just sitting there hoping the guy shoots someone else.”

To build up the confidence to go after a killer, the trainers offer historical examples of when it has worked.

Just this summer, three unarmed friends on a train headed for Paris tackled a suspected Islamist militant about to attack hundreds of passengers with guns. The shooting of then-Rep. Gabrielle Giffords (D-Ariz.) in 2011 was stopped by unarmed citizens, including a 74-year-old man and a 61-year-old woman.

One of Crane’s favorite examples is Jacob Ryker, who in 1998, on his 17th birthday, tackled a gunman at his Oregon high school — after being shot in the lung. Afterward, his mother said, “He knew he had to tackle the guy or other people would be killed.”

That didn’t happen at Virginia Tech, where Seung Hui Cho killed 32 students and teachers on campus in 2007. He stopped to reload his guns more than a dozen times.

“He wasn’t impeded in any way,” Crane said. “His victims were uninformed. That’s not their fault. We let this protocol of lockdown become a national standard.”

At NeighborWorks, employees were relieved and even excited to learn different options. The information was revelatory in ways big and small — for instance, to make sure police don’t mistake you for the gunman, get away from the gun or put it in the trash.

“I think people were really energized about taking an affirmative, offensive approach to these situations as opposed to just hiding behind a chair or something,” said McNeil, the employee who was subdued.

Tayna Frett, a senior vice president at NeighborWorks overseeing facilities, helped set up the training. The message to evacuate — not just hunker down — was so jolting that she made a point to tell her husband afterward. She felt empowered watching her co-workers control McNeil.

“They used a lot of women,” she said. “It wasn’t how big you are. It’s about the technique and using multiple people to gain control.” As she watched, she was thinking, “I can do that. I can take someone down.”

Zimmerman, with K17 Security, hopes the shift in training will itself become a deterrent. Right now, shooters know they are likely to face little resistance.

“These guys want to be famous, to be known for what they did,” he said. “If four women take him down, and that’s the news, that’s embarrassing.”

Fighting back changes the narrative.

“They’re expecting everyone to hide under a table,” he said. “That’s what they’re expecting.”

Until a book hits them in the face.