A heavily Jewish Great Neck high school has come under scrutiny after someone posted a “horrific” anti-Semitic image on the freshman class’ Facebook page.

The image is of two young children, one of whom has been Photoshopped so that he has a Hitler-style mustache and Nazi armband. Above his head it says, “I’d rather be gassing Jews right now.”

Officials from Great Neck South High School and the district said in a public letter that the Facebook page is not under the auspices of the school, but that as soon as they learned of the posting on Sunday they immediately took action to get it removed.

The student who is suspected of having posted the image attends John F. Kennedy High School in Plainview, 15 miles away on Long Island, a Plainview school official confirmed.

It is unclear how long the photo was online. The New York Observer, which broke the story Monday, quotes local residents saying that the photo was put up on Friday. But a teacher at Great Neck South High School said it was posted on Sunday. Neither school officials nor local police would confirm when it was posted.

Police said they are investigating the incident, but so far no official complaint has been filed.

Lorna R. Lewis, superintendent of Plainview-Old Bethpage Central School District, said her district is also investigating, and will take disciplinary action if the student who posted the image does go to school in the district.

She noted that JFK High School has a Holocaust education center and a yearlong Holocaust education course. “We have a very large Jewish population,” she said.

Asked whether she thought the suspected student fully understood the significance of what he posted, she said, “Children do silly things sometimes without even making a connection to how they hurt other children,” she said. “But this is a very serious offense and we take it very seriously.”

Despite the revelation that the student who posted the image comes from outside of Great Neck, Great Neck South High School is still under fire.

“We got some very, very hateful phone calls to our building today,” said social studies teacher Michelle Sorise, who teaches a yearlong course on the Holocaust. Called “Facing History and Ourselves,” the 12th grade elective takes up three periods of the day. The school also threads Holocaust education through all of its social studies courses, brings in Holocaust survivors to speak and has other Shoah-related educational activities. The school play last month, for example, was based on “The Diary of Anne Frank,” said Sorise, who leads workshops for other teachers on Holocaust education.

“It’s a little bit bothersome because I feel as though that we are leading in terms of Holocaust education,” she said.

She said that there is some friction between the school’s growing Asian population and white students, but that the school works hard to build tolerance. Anti-Semitic incidents are extremely rare, but when they happen, the school acts immediately, she said. For example, in the recent past an Asian student called another student a “dirty Jew” and was disciplined by being required to volunteer every week at the Holocaust Memorial and Tolerance Center of Nassau County.

“Now somebody in another building, a student that we don’t have any contact with, makes a comment and a horrific image and now all of a sudden our school is being labeled as one in which we’re perpetuating or we’re somewhat appeasing or not active enough in addressing anti-Semitism in our building,” Sorise said. “We require a lot more than other public schools do, and it’s a little frustrating to now have these things come out saying that we’re harboring all of these anti-Semitic feelings.”

In the public letter, Great Neck Public Schools Superintendent Thomas Dolan said the Facebook post represented “a pair of evils, one minor and one major.”

“The comparatively minor evil is the anonymity with which individuals can post on social media sites and the proliferation of anonymous, or seemingly anonymous, statements that can be made and instantaneously shared with no awareness of the damage that they can do,” he wrote.

“The major evil, one that has been seen on the world stage again very recently, is the specter of anti-Semitism and other forms of racism that one would have hoped had been eradicated by now. Sadly, we have seen it here in our District on this occasion, and we cannot and do not tolerate it in anyway,” he continued.

He said district officials would work to educate students about the repercussions of both issues and would “re-double our efforts” to “use education as a means to eliminate these hateful statements” by creating “a program for students and their parents to discuss this issue… .”

Rabbi Meir Feldman of Temple Beth-El of Great Neck said since Sunday night he has received “dozens and dozens of emails” from concerned congregants about the Facebook post. He is planning to hold discussions about the incident both in the Hebrew school and with parents.

“As a former federal prosecutor I know well the importance of advocacy — the realm of disciplinary action and enforcement of the criminal law,” he said in an emailed statement. “As a rabbi, I know well the ultimate importance of education. Quoting Rabbi [Abraham Joshua] Heschel, our aim must be the ‘education of the soul,’ of both Jewish and non-Jewish youth. This painstaking, holy and critical work can only be done one child at a time. These are the serious challenges before us.”

Meanwhile, Manhattan’s John Jay College of Criminal Justice is also dealing with anti-Semitism. On Monday, it was reported that swastikas and racist slurs were scrawled in bathrooms and in a classroom. The graffiti included two anti-Semitic messages, one racist slur and an anti-gay message.

The college’s vice president, Lynette Cook-Francis, met with representatives of the groups that were targeted in the hate messages, according to a letter written to the campus community by John Jay’s president, Jeremy Travis. College officials also met with the New York Police Department’s Hate Crimes unit.

In the fall, John Jay’s Hillel chapter faced significant anti-Israel activity through the school’s BDS movement and several Hillel members said they felt uncomfortable in the school. The student group said in a statement that it was gratified by the administration’s swift removal of the graffiti.

“It might be easy to dismiss this as a minor act of vandalism but given the rise of global anti-Semitism (including on college campuses), we must be vigilant in speaking out against all manifestations of anti-Jewish behavior and symbols.”

JTA contributed to this report.