The top of a hateful petition that circulated at a high school in Anne Arundel County, Md. (Copy of petition provided by Anne Arundel County schools)

A white supremacist petition that circulated at a Maryland high school on Friday described African Americans as a “scourge,” said they “invented” rape, stealing and basketball, and spoke of “the supreme White race.” School officials immediately denounced the document and began an investigation.

The petition, labeled Kool Kids Klan — its three K’s underlined in a thinly veiled reference to the Ku Klux Klan — has led school leaders to pledge “the strongest possible actions” against any students involved.

George Arlotto, schools superintendent in Anne Arundel County, condemned the document in a letter to parents, saying it was shared during lunch Friday at Arundel High School, in Gambrills, Md. Several students are believed to have been involved, he said, and at least two students signed the petition.

“I am shocked, dismayed, and quite frankly angered that such a piece of material would be produced, much less appear in one of our schools,” he wrote. “It is unconscionable to me how anyone could believe this material is anything but horrifying, and it has absolutely no place in our schools or school system.”

As others voiced similar reactions, Anne Arundel police on Monday afternoon began investigating what they called an “indirect threat” against the school of 2,089 students, made in a tweet. Police said the threat appeared related to the Friday incident.

“We don’t think that threat is credible, but we are taking it very seriously,” said Anne Arundel police Lt. Ryan Frashure.

Arundel High School’s principal sent home a letter to parents Monday saying that she was saddened and stunned “by the mere existence of the petition, to say nothing of the wording used in it.” But she also said she was equally heartened by the resolve of staff, parents, students and the community.

“The collective message has been clear: Arundel High School will not be defined by this incident,” Principal Gina Davenport wrote. “We will remain one community that celebrates our diversity.”

Davenport asked parents and students to join her at the school this week to discuss “where we as a community go from here.”

The petition follows a string of other hate-related incidents at schools in recent months. In Montgomery County, swastikas were found drawn on the walls of school bathrooms in a Bethesda middle school and a “whites only” sign was taped to a restroom door at a high school in Potomac. More recently, graffiti that was written onto the bathroom wall of a Silver Spring elementary school that reportedly said, “kill all whites,” according to police.

Anne Arundel Board of Education President Stacy Korbelak released a statement that sought to cast the incident in a broader light, saying the petition pointed to the intolerance that exists at all levels of society.

“This is an issue far bigger than any single school,” she said. “We are all bombarded with misguided messages on a daily basis that attempt to divide our society and create intolerance.” Korbelak asked that the community redouble its efforts to “remind each other, and especially our children, that (in the words of Dr. Martin Luther King, Jr.): ‘ . . . Hate cannot drive out hate; only love can do that.’ ”

Arlotto urged parents to have an open, honest dialogue with students.

Anne Arundel police and prosecutors met Friday about the petition but said there does not appear to be a basis for criminal charges, said Marc Limansky, a county police spokesman.

Bob Mosier, spokesman for the school system, said “appropriate disciplinary action” was being taken against those involved; he did not know how many students were connected to the petition, but he said the school’s investigation is continuing.

Mosier said efforts are underway to add lessons for students on racial and cultural tolerance and the appreciation of diversity.

Two 2014 graduates of Arundel High — Wilglory Tanjong, now a Princeton student, and Irvin McCullough, now a Cornell student — called on school officials to recognize the petition as hate speech, punish the petitioners, clarify policies toward student hate speech, and “educate students about both systemic and overt racism by hosting inclusive discussions and reshaping course curriculums.”