CHICAGO (AP) — A Catholic high school on Chicago’s South Side canceled Friday classes amid concern about a demonstration, which was later postponed, to protest the fatal police shooting of a black man and a series of racially charged text messages from students.

Eva Lewis, who helped organize the Black Lives Matter demonstration planned by youth in the Mount Greenwood neighborhood, said it was called off after the group received online death threats. She said the activists would voice their safety concerns during a meeting Friday afternoon with Chicago police Superintendent Eddie Johnson, the Marist High School principal, local officials and others.

The meeting comes amid increased tensions in the predominantly white neighborhood that is home to many police officers, firefighters and other city employees. An off-duty police officer fatally shot Joshua Beal, a 25-year-old Indianapolis resident. Police say Beal pointed a gun at the officer during a melee that began when an off-duty firefighter told the driver of the vehicle Beal was in that it needed to be moved because it was blocking a fire station’s driveway.

Since then, activists have held at least two demonstrations — both of which attracted largely white crowds that shouted profanity and racially-charged language at the protesters.

The school said in a statement on Friday that it called off classes to “ensure safety and limit learning disruptions.” School officials have launched an investigation of the students’ text messages, telling parents in a message posted online that they were “devastated by this incident” and that security at the school had been increased. The school said that “disciplinary action” was taken but did not elaborate

In his own message on the Archdiocese of Chicago website, Archbishop Blase Cupich said he supports the school taking “the necessary steps to deal with this situation swiftly and take appropriate disciplinary action.” And, he said, “Racism is a sin and has no place in the Church, including the Archdiocese of Chicago.”

In a group text, female students at the school discussed the shooting and the subsequent Black Lives Matter protests. The Daily Southtown reported one girl used the N-word, according to a screen shot shared on Twitter, while at least four others reaffirmed the racist message.