A fraternity at California Polytechnic State University was sanctioned by its national organization on Tuesday after students dressed as gang members, including one in blackface, during the college’s annual multicultural event over the weekend.

Photos first surfaced online on Sunday showing white students from Lambda Chi Alpha outside their fraternity house wearing baggy jeans, gold necklaces and bandannas as they flashed fake gang signs.

But it was another photo — of a fraternity brother in blackface — that drew swift outrage from both students and officials at the university in San Luis Obispo, Calif., leading to an almost immediate suspension of the chapter, protests on campus and a standing room only meeting with students to address racism at the college.

On Monday, the college placed Lambda Chi Alpha on interim suspension while it investigated. On Tuesday, the national fraternity office said it had placed the chapter on “limited operations,” sanctions that restrict it from participating in formal activities.