The Calabasas middle school that was shaken this month by attacks on redheads was jolted again Monday when news spread that two 12-year-olds and a 13-year-old had been arrested in the bizarre incident.

Apparently spurred by a Facebook site and inspired by the animated “South Park” television show, “Kick a Ginger Day” brought notoriety to A.E. Wright Middle School, an ordinarily peaceful campus that sponsored a tolerance assembly for students Monday in the wake of the attacks. The “South Park” episode, first shown in 2005, was itself supposed to be a lesson in tolerance but misfired, with harassment of red-haired students taking place at schools across the U.S. and Canada over the last few years.

In Calabasas, an affluent community northwest of Los Angeles, school officials have identified nine children believed to be responsible for the assaults but their investigation is continuing. Eleven victims have come forward.

All the injuries were minor, officials said.

Two 12-year-old boys are suspected of battery. A 13-year-old boy was detained on suspicion of cyber-bullying -- making a threat via the Internet -- because of his written response to a Facebook invitation to the Nov. 20 spree, according to Los Angeles County Sheriff’s Lt. John Benedict. The boys, who face possible criminal charges, were released to their parents.

Samara Kleinfinger, 12, said she and other red-haired students were summoned to the principal’s office on Nov. 20. There already had been at least one attack and administrators, alerted by students to the possibility of more, wanted to warn Samara and others to be careful.

Samara said she was punched and kicked by six students on her way to the office.

“They seemed to think it was a big, funny joke,” she said. The rest of the day, a knot of friends protected her as she made her way from class to class.

On the first school day after Thanksgiving break, principal Kimmarie Taylor cautioned students on the public address system to be mindful of their responses to reporters and news crews who had gathered on campus. At an assembly earlier, she attempted to demonstrate the irreversible consequences of ill-thought-out actions by having students try to put toothpaste back into a tube using toothpicks. Later, they wrote essays about making the school a better place.

“This was out of left field for us,” said Taylor, pointing out that the students under investigation had not been in trouble before. Some were given five-day suspensions -- the maximum allowed under state education rules -- and had already written letters of apology to the victims, she said.

“They’re all good kids,” she said. “They just made a very bad choice.”

In the show’s Ginger Kids segment, foul-mouthed Eric Cartman spreads word at school that “gingers” are genetically defective, evil, and out to get non-ginger students. But when classmates dye his hair red as he sleeps, Cartman rallies other red-haired students with chants of “Red power!” Only after inciting the red-haired kids to round up non-gingers for “extermination” does he learn that he’s been the victim of a prank. At the end, all the students sing about brotherhood.

Intended to be satirical, the show played off virally-spread events aimed at Jews, homosexuals and other minorities. But satire can be lost on the young, some experts said.

“The irony of this is, the episode that has been linked to this was in fact underscoring how hurtful, destructive and horrible bigotry is,” said Donald Zimring, superintendent of the Las Virgenes Unified School District. “That kind of lesson is a fairly complex lesson. It’s going to get lost on a 10-, 11-, or 12-year-old. . . . They don’t understand the deeper meaning.”

South Park’s writers were unavailable for comment, said a representative from the show. But the show is rated for “Mature Audiences Only.” Shows with such ratings may have content “unsuitable for children under 17,” according to Federal Communications Commission guidelines.

“Sometimes TV producers, even those wanting to represent peaceful outcomes, do negative modeling,” said Ron Slaby, senior scientist at the Education Development Center and the Center on Media and Child Health. “When you show hateful adversarial behavior or even concepts, the effect may be most pronounced with those who have the least resilience against it.”

The annual kick-a-ginger event has brought angry criticism from people who feel the show’s producers should have known better. A judge in Calgary, Canada, where 13 high school students swarmed a red-haired boy in a locker room, called the show “a vulgar, socially irreverent program that contributes nothing to society.”

In Calabasas, a parent said she knew one of the boys who was detained and described him as shy and quiet. Alexandra Townsend said the boy was recently bullied himself, tied to a basketball pole by other students.

Townsend said she’s considering private school for her daughter, Jasmine. While students had mixed opinions about the significance of the incident, parents who spoke to The Times Monday were not at all ambivalent.

“They should be very, very harsh with the punishment,” said Ruthie Stockfish, who was dropping off her daughter Ella’s clarinet. “My daughter has light-brown hair. She’s cute. Is tomorrow going to be cute-kid-hitting day?”

victoria.kim@latimes.com

richard.winton@latimes.com

Times staff writer Steve Chawkins contributed to this report.