Students in Rhode Island have shouted down New York City Police Commissioner Ray Kelly during a talk at Brown university, and his planned lecture called "Proactive Policing in America's Biggest City" was canceled.

More than 100 students and social justice activists protested the Tuesday lecture because of the department's stop-and-frisk policy and its surveillance of Muslims.

Many protesters began shouting as the lecture began. Brown officials asked protesters to reserve their comments until a question-and-answer session with Kelly. When the shouting continued, the hall was cleared.

A federal judge recently ruled the department's stop-and-frisk policy violates the civil rights of minorities. The city is appealing.

Brown spokeswoman Marisa Quinn says the Ivy League school has a tradition of open dialogue on difficult subjects. She calls the lecture's cancellation "unfortunate."