Racial tensions at a Northeast Philadelphia magnet school spilled over this week, sparking protests, a social media threat, and a heavy police presence.

The situation has been developing at the Arts Academy at Benjamin Rush on Knights Road, where half the 600-plus students are white, while just under 20 percent are black and a similar number are Latino. Asian and multi-racial students account for the rest.

Tensions had been building but began to flare last week following a Black History Month assembly, according to students. During the assembly, students said, a white student shouted racial slurs. Separately, the same student wrote a slur on a desk. This week, that student was suspended.

In an Instagram post, a member of the student group Minorities Silenced described what happened and said black and Latino students at Rush have been subjected to racial prejudice.

“Friday after our African American assembly, allegedly a white male student said that blacks don’t deserve an African American assembly, they only use it as a reason to tear whites down,” the post reads. “He also say n— are a bane of his existence. this is the same white male teenager who wrote on paper saying that n— are oogily boogily banana eating monkeys."

Principal Lori DeFields said in an email to parents Thursday that on Wednesday night, “an unknown person posted a concern that a Rush student who was recently suspended made a threat to shoot up our school. Another post indicated that this Rush student spoke to a student from another school, who then reported the information to their counselor. Concerned parents then filed reports with the Philadelphia Police Department.”

Police officials said the investigation was still active, but Lee Whack, a School District spokesperson, said there is “no further threat to the school at this time.”

No arrests have been made, according to police.

The district confirmed that attendance was down Thursday. Parents posting on social media indicated that they were too worried to let their children go to Rush despite authorities’ assurances. They lamented that the school, known for its strong academics and arts focus, was going through turmoil.

Extra police were stationed at the school, as were School District staff working to help ease tensions, Whack said.

“It’s clear that there are racial tensions at the school, among the student body,” said Whack. “We are working with the students to do social-emotional learning around these types of issues.”

Whack added that “hate speech and racial slurs are completely unacceptable.” He said the district would hire an extra Rush staffer to help with racial conflicts, and also was hoping to form a school-sanctioned minority student group.

In the days leading up to the social media threat, some Rush students of color had begun to be vocal about what they say is unfair treatment at the school. They created “Minorities Silenced” social media accounts and protested at Rush, gathering on the school steps with fists raised and tape over their mouths to symbolize being silenced. They held signs: “Y’all want silence right? Silence!”

Together with students from other schools, the Minorities Silenced group planned a protest at School District headquarters after dismissal on Friday. The demonstration has been canceled out of fear for the students’ safety.

“We were repeatedly facing racism in the way that punishments — suspensions, detentions — are carried out,” one Rush student said in an interview.

The students were upset that the white student did not face immediate consequences for his hate speech, that he was slow to be disciplined.

“I feel like I don’t have a voice at my school, like I’m treated differently. I have to censor my thoughts. I have to act a certain way,” another Rush student said. The students asked that their names be withheld because they feared retribution from peers and school staff.

The students said they felt scared by the threat to shoot up the school, but they did not regret that the racial tensions were coming to light.