A 16-year-old boy who called himself "a hater of all black men" and shot several black boxes that he said represented African-Americans in a series of videos was charged with making threats, according to media reports.
The teen - whose name has not been released because of his age - was expelled and banned from Cardinal Newman School property, the school said.
The videos were created in May, according to the paper. The school notified authorities in July.
"The next few days may be challenging for Cardinal Newman School, so I ask your prayers for our students, teachers, staff and administration," Principal Robert Loia wrote in a letter sent out Friday night.
Diocese of Charleston spokeswoman Maria Aselage said church officials determined the danger to students was minimal since the school was out and police were investigating.
On Monday, many parents at a morning meeting with Loia criticized the school for failing to notify them about the videos last spring.
"I realize now that I should have communicated with you immediately when I learned a violent threat had been made against our school community," Loia wrote in a letter released Monday night.
The Associated Press contributed to this report.