CUPERTINO — The parent of a black student at Monta Vista High School has filed a lawsuit against the Fremont Union High School District, alleging the district failed to take proper disciplinary action against several students who created a “kill list” targeting black students, including her own child.

An attorney for the family said administrators failed to disclose the list to black students or to law enforcement authorities when the social media posts first surfaced in September, which the district contends. The lawsuit, filed in Santa Clara Superior Court, also claims the district violated federal and state civil rights claims and state education codes by failing to prevent discrimination against black students and failing to enforce anti-bullying policies.

“The students themselves had no idea that their lives were being threatened,” said community activist Walter Wilson during a press conference Tuesday in San Jose. “The parents had no idea they were sending their kids to school in what they thought was a safe environment, which clearly it was not or may not have been.”

The alleged “kill list,” which was created by 6 to 10 non-black students and shared on Instagram and Snapchat, according to activists and the teen’s attorney, included intentions to “shoot and kill all black students at the high school.” It referred to black students with a racial slur and also included misogynistic comments toward female students.

District and sheriff’s officials did not say whether the offensive list appeared to be a legitimate threat to harm students or an inappropriate attempt at humor. But the activists said they were treating it as a serious threat and likened it to the antisocial ramblings of two students who massacred their classmates in 1999 at Colorado’s Columbine High School.

“This is not a joke,” said Richard Richardson, the girl’s attorney. “This is a credible threat that almost rises to the level of being a criminal threat.”

Community leaders allege the incident points to a culture of discrimination toward black students at the school, of which there are only five — about 0.2 percent of the student body — according to data provided by the district. About 1,831 or about 78.4 percent of the student body are Asian; 335 or 14.4 percent are white; 75 students or 3.2 percent are two races or more and 68 or 2.9 percent are Latino.

It’s one of the latest racially-charged incidents to surface at schools across the Bay Area and beyond, prompting some parents and advocates to question whether school administrators are doing enough to provide a safe learning environment for their kids, free of discrimination.

A Fremont Union High School District representative said the district is aware of the incident but has not yet been served with the lawsuit. Richardson said they will likely be served by the end of the week.

“When it was first brought to the attention of administrators at Monta Vista High School, staff immediately investigated and took appropriate disciplinary action. Administrators also immediately contacted the Santa Clara County Sheriff’s Office, due to the seriousness of the speech, and as we do with any issue where we believe safety is involved,” a district spokeswoman said in a prepared statement. “Personnel from the Sheriff’s Office investigated and interviewed the students involved the day after the incident was reported to staff; both those that had written the offensive language and those that were the witnesses/victims involved in the social media chat that occurred.”

In a statement attributed to Sheriff Laurie Smith, the Santa Clara County Sheriff’s Office said it began an investigation into the incident in September and recently turned over its findings to the District Attorney’s office “for criminal prosecution.”

“We are required to protect the privacy of all the minors involved and we are unable to disclose the details of the investigative findings to protect the integrity of the investigation,” Smith said in the statement.

The girl targeted in the posts, who was 16 at the time of the incident, transferred out of Monta Vista but remains in the district, Richardson said.