A Missouri school district has been left reeling after several high-school students reportedly started a petition demanding the reinstatement of slavery, The Kansas City Star reports. Details on the incident are scarce, with a spokesperson for the Park Hill School District confirming only that there was a “discipline incident” at Park Hill South High School last week and several school officials releasing statements that allude to racism. “We are outraged, hurt, and saddened that this occurred,” Park Hill South Principal Kerrie Herren said in a statement to students. “This is not who we want to be at Park Hill South. Our differences make us stronger. We do not tolerate discrimination or harassment.”

Parents also were reportedly told via email of “unacceptable and racist statements that some students posted online during a school-related activity.” The principal of another high school within the district is said to have confirmed to parents at a Monday meeting that the incident in question was a racist petition. It was not immediately clear how many students were involved in the incident, and what “school-related activity” prompted it. The district says it has set up listening sessions to hear from students and parents affected by the petition.