Berkeley, California -- Violence erupted Wednesday night at UC Berkeley -- the same campus where the Free Speech Movement started 53 years ago -- hours before right-wing commentator Milo Yiannopoulos was scheduled to speak.
The university blamed "150 masked agitators" for the unrest, saying they had come to campus to disturb an otherwise peaceful protest.
Administrators decided to cancel the event about two hours before the Breitbart editor's speech.
UC Berkeley said it removed him from campus "amid the violence and destruction of property and out of concern for public safety."
Black-clad protesters wearing masks threw commercial-grade fireworks and rocks at police.
Some even hurled Molotov cocktails that ignited fires.
They also smashed windows of the student union center on the Berkeley campus where the Yiannopoulos event was to be held.
At least six people were injured.
Some were attacked by the agitators -- who are a part of an anarchist group known as the "Black Bloc" that has been causing problems in Oakland for years, said Dan Mogulof, UC Berkeley spokesman.
More than 1,500 protesters had gathered at Sproul Plaza, chanting and holding signs that read: "No safe space for racists" and "This is war."
The violent protesters tore down metal barriers, set fires near the campus bookstore and damaged the construction site of a new dorm.
One woman wearing a red Trump hat was pepper sprayed in the face while being interviewed by CNN affiliate KGO.
She was able to respond that she was OK after the attack.
As the scene spiraled out of control, university police warned protesters to disperse and issued a lockdown for campus buildings.
"We condemn in the strongest possible terms the violence and unlawful behavior that was on display and deeply regret that those tactics will now overshadow the efforts to engage in legitimate and lawful protest against the performer's presence and perspectives," UC Berkeley said in a statement.
"While Yiannopoulos' views, tactics and rhetoric are profoundly contrary to our own, we are bound by the Constitution, the law, our values and the campus's Principles of Community to enable free expression across the full spectrum of opinion and perspective," it stated.
As police dispersed the crowd from campus, a remaining group of protesters moved into downtown Berkeley and smashed windows at several local banks.
No arrests were made throughout the night.