A Northern California teacher wore blackface on Halloween and imitated rapper and social activist Common, according to local reports. The Milpitas Unified School District staff member has been placed on administrative leave after his students posted videos of the shocking incident online. The teacher appeared to imitate Common—who is also the face of an advertising campaign for Microsoft’s artificial-intelligence technology—in front of a full classroom. One of the students said the teacher is white and teaches at “mhs,” or Milpitas High School, according to The Mercury News. The name of the teacher hasn’t yet been confirmed. School Board President Chris Norwood said in a statement Sunday: “The action(s) were inappropriate, unprofessional and insensitive.... District administration has placed the staff member on administrative leave and I have asked the superintendent to ensure an immediate investigation is conducted.”