In the latest crackdown by less than tolerant liberals against free speech, on Wednesday night hundreds of protesters at University of California in Berkeley smashed windows, set fires and clashed with police as they forced a controversial "alt-right" speaker to cancel his appearance at the liberal-leaning institution.

Two hours before Breitbart News editor Milo Yiannopoulos was to give a speech at the student union, protesters tossed metal barricades and rocks through the building's windows and set a light generator on fire near the entrance, footage from news outlets showed

Police ordered protesters to disperse as the school put the campus on lockdown. Protesters also tossed bricks and fireworks at police in riot gear who fired rubber pellets back at the crowd, according to SFGate.com, a news outlet in San Francisco.

"We shut down the event. It was great. Mission accomplished," a protester told CNN.