Tulane University police officer Martinus Mitchum, who was working security for the George Washington Carver High School basketball team in New Orleans this weekend was shot and killed after he went to help another staff member that was punched by a man trying to enter the game without a mask on.

As reported by the Washington Post, John Shallerhorn, who has already confessed to the killing, punched a staffer after Shallerhorn was asked to put a mask on. Mitchum came to help and Shallerhorn pulled a gun and shot Mitchum.