The killings are happening too often. Bunched too close together. At places you would never imagine.

As the long roll call of mass shootings added a prosaic holiday party in San Bernardino, California, to its list, a wide swath of America’s populace finds itself engulfed in a collective fear, a fear tinged with confusion and exasperation and a broad brew of emotions. The fear of the ordinary. Going to work. Eating a meal in a restaurant. Sending children to school. Watching a movie.

Wendy Malloy, 49, who lives in Tampa, Florida, said she now worried about being caught in an attack on a daily basis, just doing what anyone does. “When my son gets out of the car in the morning and walks into his high school,” she said. “When I drop him at his part-time job at a supermarket. When we go to the movies, concerts and festivals. When I walk into my office. It is a constant, grinding anxiety. And it gets louder every single day.”

After all, a festive gathering of county health workers in San Bernardino would not seem likely to make the top million of a list of shooting targets. It was not an iconic symbol of American freedom or American muscle. It was not a target draped in ideological conflict.

If you were not safe there, where were you safe? A common office party. That was everywhere. That was everybody.

A complicated tangle of emotions has taken hold. For some, the shock of repeated slaughters is leaving them inured and resigned. With others, there is recurrent bewilderment. And anger. Why doesn’t the government and law enforcement do more? Why must I feel so helpless? What world must my children live in? Why won’t it stop already?

Jean O’Sullivan, 54, who lives in the Los Angeles area and thinks about shootings multiple times a day, wrote, “Just as I naturally consider how I would survive if there was an earthquake, now I have added mental contingencies for a shooting — and THAT is a sad state of affairs!”

In the aftermath of the San Bernardino shootings, coming close on the heels of the Colorado killings, The New York Times invited people to respond online about their fear of a mass shooting.

More than 4,000 responded. In addition, many others were interviewed Thursday around the country: teachers and students and office workers, even some Army veterans who confided that they felt safer in war zones than on the streets of the United States.

People spoke of being spooked by gestures once ignored as utterly unremarkable. As one young woman from Massachusetts put it: “The guy in the corner always looking at his watch or the woman reaching into her bag too quickly.”

Of course the man is probably wondering where his date is already. Of course the odds are the woman simply heard her cellphone vibrate.

But is it? Could it be? Must I run?

This woman said she planned to have children in the future, probably not for a decade, and yet she had already made the decision to home school them.

By no means is this deep anxiety causing life to grind to any sort of standstill. Many Americans remain steadfast that they will not crumple in the face of terrorists or other strains of mass murderers, foreign or homebred. Some want to buy their own gun. Many insist they worry to a greater extent about a car accident or slip in the bathtub befalling them, statistically more probable events than gun atrocities. People work, go out, live. But still, a creeping fear of being caught in a mass rampage has unmistakably settled itself firmly in the American consciousness.

Any number of people said that gunmen cross their mind when someone gets up or walks in late to a crowded movie theater. Is he the one? A 64-year-old man in Charlottesville, Virginia, said he now watched movies exclusively at home. For him, he said, the idea that “it can’t happen here” is gone.

Others feared that whenever a work colleague was fired, he would return armed and shooting.

Arthur Grupp, 64, who is the head custodian of an elementary school in New Hampshire, said, “Every time I lock the doors at school, I think about it.” His school was having a Homeland Security training session just as the violence in San Bernardino unfolded.

A person in Denver said that not long ago the fear used to enter his mind every few weeks. Now it is at least once a day: “Because at any moment it could be my little brother at school, my siblings running errands, my parents at work, me on my way to class who could be the next name having ‘thoughts and prayers’ sent their way.”

A 23-year-old woman in Cleveland said that she was frightened of doing anything and that she “hated this world.”

“Everybody is filled with what we sometimes refer to as anticipatory anxiety — worrying about something that is not currently happening in our lives but could happen,” said Alan Hilfer, the former chief psychologist at Maimonides Medical Center in Brooklyn who is now in private practice. “And they are worrying that the randomness of it, which on one hand makes the odds of something happening to them very small, that randomness also makes it possible to happen to them.”

People are able to recite with precision how often they think about a mass shooting touching them. Every day. Twice a week. Up to four times a day. Every other day. Every two weeks. Every time they’re in a crowded space. Whenever her teenagers are out. Every time she walks into her office and back to the parking garage. Every day. Every day. Every day.

For a 16-year-old in Berkeley, it is “almost constantly.”

Tracy Gill, 32, works at the Joe Van Gogh coffee shop in Durham, North Carolina. She finds herself being much fussier about her public activities. No movies on opening night. When she goes to a theater, she always sits in the back.

“If there’s a possibility of there being any kind of danger, I’ll just pick and choose what I’m going to go to,” she said. “Is it even worth it? I hate that that’s even a thought in my head.”

A 32-year-old woman in Green Bay, Wisconsin, said that she and her husband discussed a plan whenever they were heading to a place that could be a target. Now, she feels that is everywhere.

Judith Mitchell, 62, who lives in Austin, Texas, and works for the state, has four grandchildren and is exasperated that her country cannot solve this. She does not see why she must live how she does.

“If I’m in a shopping mall,” she said, “I’m always aware of what’s around me and where I can hide, the closest exit, where to go, especially if I have a grandchild with me.”

Kevin Bloxom, 50, who lives in Louisiana, wrote, “I think where I would hide my kids from shooters every time I am in public. No matter where. Not just movies or public events. I was in the grocery store last weekend with my 4-year-old. I found myself scouting places I could hide my little boy. It’s sad.”

The fear sneaks up on some people, catches them off guard. Amanda Cusick, 23, a law student in San Francisco, said that with school demands she barely has time to worry about anything. “I don’t wake up and think, what if I’m shot today?” she wrote. But then she will be driving or in a meditative moment, and she thinks, what if her younger sister is shot and she never sees her again? Does she know who to contact for her parents’ will?

On Wednesday, after news of San Bernardino had filtered in, a spontaneous discussion began among several co-workers at a Department of Veterans Affairs medical center in Manhattan. The subject was which room to lock themselves in should a shooter arrive.

Emily Johnston, 26, a college student in Cincinnati, said that a year ago there was a threat against her university involving guns and explosives. Ever since, she worries about an attack multiple times a day.

She steers clear of crowded areas. And the fear infects her sleep. “I have had nightmares in which I am sitting in class when a gunman enters,” she wrote. “I realize I have nowhere to go and feel trapped, panicked, helpless. In another nightmare, students are running from a shooter in one building but there are more than one and another is waiting.”

How does one navigate this swirl of emotions?

“I think awareness of your own fears is the only way to go and to do the things that are soothing and comforting and distracting to do, and to do things that bring meaning to your life and bring comfort to other people,” said Dr. Sherry Katz-Bearnot, assistant clinical professor at Columbia University College of Physicians and Surgeons. “It’s what your grandmother said: keep busy.”

Some people find that they have reached a numbed state of resignation.

Eric Hsu, 37, who lives in Los Angeles and shoots videos for a living, said that because of the volume of massacres, the San Bernardino shooting “didn’t even register amongst my friends and family during dinnertime conversation or on social media.” It was too common.

“I saw a picture of a woman being taken out on a gurney,” he wrote. “I go to buildings just like the one in San Bernardino all the time. I do my work with innocent and unsuspecting people. Life is fine until it happens to you. That’s how I feel about it now. I’m fine. Until it happens to me.”

© 2015 The New York Times Company