The unwanted were turned away from cafeteria tables. Fistfights broke out at karaoke. Dances became breeding grounds for gossip and cruelty.

It became clear this place had a bullying problem on its hands. What many found surprising was that the perpetrators and victims alike were all senior citizens.

Nursing homes, senior centers and housing complexes for the elderly have introduced programs, training and policies aimed at curbing spates of bullying, an issue once thought the exclusive domain of the young.

"There's the clique system just like everywhere else," said Betsy Gran, who until recently was assistant director at San Francisco's 30th Street Senior Center. "It's like 'Mean Girls,' but everyone is 80."

After the cafeteria exiles and karaoke brouhahas, the 30th Street Center teamed up with a local nonprofit, the Institute on Aging, to develop an anti-bullying program. All staff members received 18 hours of training that included lessons on what constitutes bullying, causes of the problem and how to manage such conflicts. Seniors were then invited to similar classes, held in English and Spanish, teaching them to alert staff or intervene themselves if they witness bullying. Signs and even place mats around the center now declare it a "Bully Free Zone."

"I think in the past I would have just stayed out of it," said Mary Murphy, 86, a retired real estate agent who took the classes. "Now I might be inclined to help."

Volunteer program manager Kathy Blando (right) talks to students during an anti-bullying class at the 30th Street Senior Center in San Francisco on April 13, 2018. Marcio Jose Sanchez | Associated Press

Robin Bonifas, a social work professor at Arizona State University and author of the book "Bullying Among Older Adults: How to Recognize and Address an Unseen Epidemic," said existing studies suggest about 1 in 5 seniors encounters bullying. She sees it as an outgrowth of frustrations characteristic in communal settings, as well a reflection of issues unique to getting older. Many elderly see their independence and sense of control disappear and, for some, becoming a bully can feel like regaining some of that lost power.

"It makes them feel very out of control," Bonifas said, "and the way they sort of get on top of things and make their name in this new world is intimidating, picking on people, gossiping."

There is far less recognition of bullying as a problem among seniors compared with young people. Even among those who have been called bullies, many are unaware how problematic their behavior is until it's labeled. Campaigns around the country have sought to spread the word, including a booklet circulated last year by the National Center for Assisted Living.

"In the life cycle, it doesn't go away," said Katherine Arnold, a member of the city Human Rights Commission in St. Louis Park, Minn., which created a public service announcement on its community-access station that included a portrayal of a man who was excluded from a card game and became the subject of gossip by other seniors. "There's really not a lot of escape."

Most senior bullying isn't physical but rather involves name-calling, rumors and exclusion, said Pamela Countouris, a longtime schoolteacher who now runs a Pittsburgh-based consultancy that offers training on bullying. Women constitute the bulk of the bullies Countouris encounters among seniors, a reflection of lifespan disparities and the gender makeup of those who live at or participate in programs at senior facilities.

Countouris' business began with a focus on school bullying but now centers exclusively on seniors. In the next month alone, she has more than a dozen training sessions planned.

After four years immersed in the wrath of older bullies, Countouris has heard all manner of stories. At a senior high-rise, a woman who saw herself as the queen of the parking garage would key the cars of those who crossed her. Elsewhere, laundry rooms became vicious places where the bullied had their detergent stolen and their clothes thrown on the floor. Bingo rooms so often devolved into battlefields — with lucky newcomers badgered and accused of cheating by veteran players — she came to call it "the devil's game."

"I didn't realize it was an underground society where people could be mean to each other," Countouris said.

Marsha Wetzel sits for a portrait in her room at Glen Saint Andrew Living Community in Niles, Ill., in January 2017. Wetzel moved into the senior apartment complex after her partner of 30 years died. She said she was met with relentless bullying by residents mostly focused on her being a lesbian. Chris Sweda | Chicago Tribune via AP 2017

In the worst cases, bullying goes far beyond bingo squabbles. Marsha Wetzel moved into a senior apartment complex in Niles, Ill., after her partner of 30 years died and her partner's family evicted her from the home the couple shared. At Glen St. Andrew Living Community, she said she was met with relentless bullying by residents mostly focused on her being a lesbian.

One man hit Wetzel's scooter with his walker and unleashed a barrage of homophobic slurs. A woman rammed her wheelchair into Wetzel's table in the dining room and knocked it over, warning "homosexuals will burn in hell." In the mailroom, someone knocked her in the head, and in an elevator, she was spit on.

"I'd just go in my room and barricade my door and just pray," said Wetzel, now 70 and living at a senior complex in Chicago. "I just felt like a slug, like I was nothing, like I wasn't even human."

Lambda Legal, which defends LGBTQ rights, took on Wetzel's case and sued Glen St. Andrew, claiming Fair Housing Act violations. A federal judge dismissed the suit last year. An appeals court decision is pending.

Wetzel had seen such bullying throughout her life. She dropped out of high school when she became a punching bag for the girls who learned she was a lesbian. As a senior, she said, it felt even more traumatic — and the bullies even more vicious. She had a view of a cemetery from her window and would stare at it, thinking maybe only when she arrived there would she find peace.

"I felt like a person in a pool of piranhas," she said.