A swastika was found drawn on a classroom desk at a suburban Maryland high school last week, authorities said.

The hate symbol, reported by a student during a lunch period at Winston Churchill High School in Montgomery County, was immediately reported to police, according to a letter sent home to parents by Principal Brandice Heckert.

The incident at the Potomac school happened Oct. 25, two days before a gunman killed 11 people at a Pittsburgh synagogue in the deadliest anti-Semitic attack in U.S. history.

The tragedy has intensified debate about political discourse in America.

Heckert said in her letter last week that the graffiti was removed by building services workers and that the school is investigating. She noted that “in the eyes of the law, it can be considered a hate crime or bias-based crime.”

“This type of behavior will not be tolerated at Winston Churchill High School and those found responsible will be subject to disciplinary actions aligned with the Student Code of Conduct,” she said.

Montgomery County Public Schools spokesman Derek Turner said the incident was the first reported this school year in the state’s largest school system, with 206 schools.

Churchill has a significant population of Jewish students and has had several anti-Semitic incidents in recent years, said Guila Franklin Siegel, who oversees education outreach as associate director at the Jewish Community Relations Council of Greater Washington.

Still, she said, “it would be wrong to assume students in middle school and high school uniformly know the history of the swastika, and why it is such a trigger, as we get farther away from the Holocaust and fewer Holocaust survivors are alive.”

Siegel said educators and Jewish leaders have a responsibility to teach students about history.

“Our concern is about raising children who understand the perniciousness of anti-Semitism, and of all bias and intolerance, because these are the future leaders,” she said.

Two years ago, bias incidents surged in Montgomery County, particularly following the 2016 presidential election.

A Washington Post analysis of county school and police information showed more than three dozen bias incidents in the 2016-2017 school year were linked to schools, mostly involving vandalism with swastikas, racial epithets or other bigoted messages.

Last school year, two swastikas were reported, Turner said. One was drawn in an elementary student’s assignment book, and another was discovered on a middle school desk.

In neighboring Washington, a swastika sticker was found on the wall in a high school bathroom Monday. Police are investigating the incident at the School Without Walls.