A nagging bunch of anxieties drove JoElla DeGrio and Barbara Sussman to a high school in Woodstock this week for a class on surviving a mass shooting.

Neighbors from Acworth, the retirees inventoried their fears as they settled into a pair of blue upholstered seats in the Etowah High School auditorium: Islamic State terrorists, “crazies” inspired by them and attacks on public places like the church and ballparks they frequent.

DeGrio and Sussman are among many Atlanta area residents flocking to so-called “Civilian Response to Active Shooter Events” seminars following a string of highly publicized shooting massacres. On edge from a steady stream of tragic news, those showing up for the discussions are looking for ways to protect themselves in case they are caught in the middle of a slaughter.

“The world is so scary now,” said DeGrio, a retired airlines industry worker who worries someone could hijack the plane she will fly on this spring for a vacation cruise in Alaska. “It’s a different world than what I grew up in.”

Sussman cited the mass shootings in Paris; San Bernardino, Calif; and the Aurora, Colo., movie theater.

“There have just been so many,” the retired legal secretary said, her expression conveying a mixture of distress and exasperation.

Local police say are now leading more of these how-to sessions — in schools, churches and businesses — because of heavy demand. People packed the 800-capacity Marietta High School auditorium last month for a similar two-hour discussion. More than 130 showed up for one at Reinhardt University in North Georgia Sunday. Another one is planned for Jan. 21 at First Baptist Church of Woodstock. Gwinnett County police are planning to offer a course. Atlanta police say they also have some events in the works.

Tuesday’s discussion at Etowah High School drew about 150 people. Most were older, though some families with children showed up. Grim-faced and quiet, they immediately fell into rapt attention.

The tension in the room was palpable as the two-hour session got under way. Pacing in front of the stage, two uniformed Cherokee County sheriff’s deputies sought to break the ice with some humor. Chief Deputy Joe Perkins joked the session would not turn the audience into “ninjas.”

“You are not going to be SEAL Team 6 rappelling off the roof when you get out of here,” he said, eliciting nervous laughter from the audience. “But we are going to give you some food for thought. You will be able to make a plan.”

Then Perkins and Deputy Jeremy Herrin took the audience through a course developed by the Advanced Law Enforcement Rapid Response Training Center at Texas State University. The center — now running about 100 training sessions a year for police to teach the course to civilians — stresses three things: Avoid, deny and defend.

First, the Cherokee deputies stressed avoiding getting hurt by being aware of exits and fleeing at the sound of the first gunshot. If you are trapped in a room, they said, turn off the lights and deny entry by barricading the door with anything heavy you can find. And as a last resort, they said, defend yourself as if it’s a fight to the death.

“Go after the weak points — eyes, the soft parts of the body. You know what I’m talking about,” Perkins said. “Don’t fight fair.” At one point, he suggested picking up a fire extinguisher, spraying the attacker in the face with it and then “beat the snot out of them with it.”

At times graphic, the presentation included a desperate 911 call from the 1999 massacre at Columbine High School; video footage of the bloody carnage from the 2008 terror attacks in Mumbai, India; and an account from a woman who described how she played dead to survive the 2007 mass shooting at Virginia Tech.

Gary Francois sat by himself across the aisle from DeGrio and Sussman, taking it all in. A network engineer from Holly Springs, he was there to learn how to protect his wife and six children.

“We are living in dangerous times now,” he said glumly. “You have to be prepared.”

Francois said he tries to not let his wife see him worried. But it’s getting to the point now, he said, where people can’t go to the mall without being concerned. Frustrated, he bemoaned how his children sometimes go out in public “willy-nilly.” He urges them to keep their wits about them, worrying what could happen at the supermarket, even his workplace.

Measuring fear on a scale of 1 to 10, Francois said he is at 7 or 8.

“Some of these folks are crazy,” he said. “You never know.”

Mike and Tiffany Brasser of Acworth went to the seminar with their young daughters, Olivia and Crystal. Mike mentioned the attacks in San Bernardino and a recent road rage shooting in Woodstock, saying, “The news is worse and worse every day.” He conceded he was even cautious walking into the Etowah auditorium, even though many armed law enforcement officers were on hand.

Brasser found the seminar helpful. He cited the lessons to “avoid” and “defend.” He couldn’t remember the third point. His daughter, Crystal, quickly added: “Deny.” She said she picked up another interesting tip from the discussion: Use your belt to secure a door from the inside, if you are trapped by a gunman. Olivia was intrigued by the video of the Virginia Tech survivor.

Asked why they showed up for the talk, their mother lovingly glanced at her two daughters and said simply: “We worry about our children.”