The Berkeley College Republicans said its "constitutional right to free speech was silenced by criminals and thugs."

"Their success is a defeat for civilized society and the free exchange of ideas on college campuses across America," it said in a statement.

The university, which had requested assistance from police in nine UC campuses, sent a notice to all students earlier Wednesday that warned of crowds near the student union, where the 500-seat, sold-out event was scheduled.

Yiannopoulos' talks have sparked protests, shouting matches and occasional violence at stops around the country. A man was shot and wounded at protests outside his Jan. 21 talk at the University of Washington.

Rowdy protests at UC Davis Jan. 13 prompted campus Republicans to cancel his appearance at the last minute. His final stop was supposed to be UCLA on Thursday but the invitation was rescinded, making Berkeley his grand finale.