CHICAGO (AP) — Dozens of students protesting the war in Gaza walked out of the University of Chicago’s commencement Saturday as the school withheld the diplomas of four seniors over their involvement with a pro-Palestinian encampment.

The disruption to the rainy two-hour outdoor ceremony was brief, with shouts, boos and calls to “Stop Genocide.” A crowd of students walked out between speeches, and a demonstration followed the official ceremony. Some chanted as they held Palestinian flags, while others donned traditional kaffiyeh, black and white checkered scarves that represent Palestinian solidarity, over their robes.

Four graduating seniors, including Youssef Haweh, were informed by email in recent days that their degrees would be withheld pending a disciplinary process related to complaints about the encampment, according to student group UChicago United for Palestine.