These days, when Eddie Chavez supervises the self-checkout area at the Safeway supermarket where he works in Colorado, he swivels his head back and forth like a pendulum, keeping a constant watch on everyone who comes through the door.

Chavez has worked in grocery stores for four decades, and he never used to feel unsafe. But now “you just never know anymore when it’s going to be the next one,” he said.

Earlier this week, a gunman opened fire inside a Kroger supermarket outside Memphis, turning the routine task of grocery shopping into a terrifying encounter with gun violence.

Such events are no longer exceptional: at least three other deadly shootings have taken place at supermarkets this year, continuing a recent trend.

According to data from the Federal Bureau of Investigation, shootings at grocery stores have risen in recent years. Between 2000 and 2020, 78 people were killed in 28 such incidents, FBI data shows.

While some of the shootings were at smaller markets or convenience stores in gas stations, major chains such as Walmart and Kroger have experienced multiple shootings at their locations since 2018. Earlier this year, a gunman killed 10 people at a King Soopers outlet, owned by Kroger, in Boulder, Colo.

For grocery workers, the threat of violence adds to a growing list of hazards they have faced during the pandemic, from an increased risk of coronavirus infection to belligerent customers refusing to wear masks.

Such jobs are often low-paying and physically demanding, said Vaile Wright, a psychologist and senior director of health care innovation at the American Psychological Association. “You’re constantly dealing with a public that has become increasingly less civil and you are knowingly putting yourself and your family at risk every day,” she said.

When a shooting like the one on Thursday occurs, grocery workers “can’t help but identify with it,” said Wright. “At a certain point, these cumulative stressors start to take a toll on your coping ability.”

For Kroger in particular, it has been a devastating year. In March, an employee opened fire at one of the company’s distribution centers in Wisconsin, killing two of his colleagues before turning the gun on himself. Just five days later, a gunman stormed into the Kroger-owned store in Boulder. The dead included three Kroger employees, six customers and a police officer.

“Nothing can prepare you for this kind of situation,” said Tim Massa, a senior vice president at Kroger, during a panel on workplace violence organized earlier this summer by a food industry group. “So many feelings wash over you – you’re fearful, you’re angry, you’re feeling the pain and importantly, just helplessness.”

Massa described how Kroger consulted experts on trauma and resiliency, held a companywide moment of reflection for the victims and urged all managers to create space for employees to discuss their feelings, reinforcing that “it’s OK not to be OK,” he said.

Kroger also required all its employees to complete a refresher course on what to do in an active-shooter situation to “ensure that everyone had a fresh recall of how they can protect themselves at work and also out in the community,” said Massa.

On Thursday, a gunman entered a Kroger store in the Memphis suburb of Collierville and began shooting. Employees rushed to hide in freezers and offices while trying to help gravely injured colleagues. One customer was killed, as was the gunman, who turned the weapon on himself.

The wounded included 10 employees and five customers, said Kristal Howard, a Kroger spokeswoman. The company is helping store employees with pay and counseling services, she said. The suspect has been identified as a “third-party vendor,” said Howard.

Lonnie E. Sheppard Jr., the president of the local chapter of the United Food and Commercial Workers International Union, said that supermarkets are clearly targets for violence and corporations must do more to protect their workers. “People need to go to work knowing they are safe,” he said.

The violence in Collierville occurred just six months and a day after the mass shooting at King Soopers, a Kroger-owned grocery store in Boulder. Employees at another King Soopers location in the same city said the shooting is never far from their minds.

Dayna Korfitzen, who works as a barista, feels safe at work because armed security personnel have been posted there since the March shooting. But she has taken note of Kroger outlets as a recurring target. “It definitely seems like Krogers are the new hot spot,” she said.

Korfitzen said the company sent out an email to employees offering counseling resources after Thursday’s shooting in Tennessee.

People pray during a vigil at the Collierville Town Hall on Friday in Collierville, Tenn. The vigil is for the person killed and those injured when a gunman attacked people in a Kroger grocery store Thursday before he was found dead of an apparent self-inflicted gunshot wound. Mark Humphrey/Associated Press

Grocery stores have been a recurrent setting for this kind of violence in part because they are open from early morning until late at night, they cater to a broad demographic range which occasionally results in interpersonal friction, and, even in the pandemic, they have been one of the few retail environments that were consistently open, says William Flynn, co-founder of the Power of Preparedness, a security training company, who formerly worked for the New York Police Department and the Department of Homeland Security.

Shootings are “certainly a problem that grocery stores are recognizing,” said Alex Balian, a retail consultant and former grocery owner with decades of experience in the industry. “It obviously doesn’t happen every week, but they have definitely increased.”

Grocery chains are not eager to discuss publicly the measures they are taking to respond to the threat. Walmart, Publix and Wegmans did not respond to requests for comment. Whole Foods said it had no one immediately ready to speak about the company’s emergency preparedness.

Rob Bartels, the former chief executive of Martin’s Super Markets, a grocery chain in Indiana and Michigan, said that the industry has a “long history of vigilance” when it comes to food safety and readying employees for threats such as armed robbery. But in 2014, those preparations at his company did not include an active-shooter situation. That changed dramatically after a gunman walked into a Martins store in Elkhart, Ind., and killed an employee and a customer.

The company organized support groups for employees across its locations to grieve and began a “vast” review of its policies and procedures in consultation with law enforcement, Bartels said. Some of the subsequent changes were physical – ensuring that all doors could be opened immediately and were numbered on the inside and out to improve communication with law enforcement in an emergency – while others focused on staff training.

Each time another grocery store shooting occurs, it brings Bartels back to that day. “You revisit it, and your heart just goes out to everybody involved because you know that kind of pain,” he said.

Two years ago, Walmart and Kroger responded to a spate of deadly shootings by asking their customers not to display weapons in stores located in states that permit the open carrying of firearms. In response, some gun rights advocates called for a boycott of the stores.

By the grim standards of American mass shootings, Thursday’s incident at the Kroger store in Tennessee barely registered – and some grocery workers elsewhere in the country said they weren’t even aware of it.

When told about what happened, Ray Fix, a 39-year-old dairy manager at a ShopRite in New Jersey, let out a long sigh. “It’s absolutely a terrible thing,” he said. But the coronavirus pandemic is a far bigger concern to him. Some customers don’t wear masks and mock store employees who do, while others get enraged by product shortages, said Fix. His store is short-staffed. Everyone is tired. “It’s a big, jumbled mess,” he said. “We’re all worn out.”

Other grocery workers, such as Safeway’s Chavez, were hyper-aware of the shooting. He’s a member of the executive board for the local chapter of the union representing grocery workers. In March, he drove to the site of the shooting in Boulder to pay his respects. He says that the union is advocating for armed guards in stores, and that the deadly violence in Tennessee makes that priority even more urgent.

“We’re putting our lives on the line all the time with coronavirus and now with all these mass shootings,” Chavez said. Employees and customers alike feel vulnerable, he said. “Like me, they’re thinking, ‘Hey, are we next?’ ”