The University of Chicago announced classes would be canceled Monday after the FBI alerted school officials that someone posted a threat of gun violence online. University President Robert Zimmer issued a letter Sunday to announce the cancellation of all classes and activities on the Hyde Park campus through midnight Tuesday. The individual reportedly mentioned targeting the “campus quad” on Monday at 10 a.m., according to the letter. Zimmer also asked those who will be on campus to remain indoors as much as possible, including students in college housing. The school will also increase police presence across the campus.