BERKELEY, Calif. _ They dressed "like ninjas" and marched onto UC Berkeley's Sproul Plaza like a paramilitary force armed with bats, steel rods, fireworks and Molotov cocktails, officials say.
The scheduled appearance Wednesday of conservative provocateur Milo Yiannopoulos was still two hours away, but it was precisely the time that most local television stations were beginning their live 6 p.m. broadcasts.
Within minutes, the group of 100 to 150 protesters had smashed half a dozen windows with barricades, launched fireworks at police and toppled a diesel-powered klieg light, which caused it to burst into flames.
"They didn't come to lock arms and sing 'Kumbaya,'" said Dan Mogulof, assistant vice chancellor and spokesman for the University of California, Berkeley.
While so-called black bloc agitators have become a fixture of Bay Area demonstrations in the past decade, their appearance at Berkeley Wednesday and otherwise peaceful demonstrations threatens to inflame tensions in an already polarized nation.
Moving officers into Wednesday night's melee, would have created "a lethal, horror situation," said campus Police Chief Margo Bennett.
"We have to do exactly what we did ...: to show tremendous restraint," she said.
UC Berkeley officials are talking with federal and local law enforcement agencies about how to address black bloc tactics, which first appeared in Europe in the 1980s but have become increasingly common in the United States in recent years.
The University of California system has had larger disruptions by students. Window-breaking and barricade tossing were common during regents' meetings when tuition was being raised significantly in the last decade, and protesters at the University of California, Los Angeles, trapped the regents and other university officials in a building and garage.
But even though there was only one arrest Wednesday night, Berkeley officials say the incident was something altogether new.
"We have never seen this on the Berkeley campus," Mogulof said. "This was an unprecedented invasion."
Mogulof said Berkeley administrators are dedicated to protecting the First Amendment and free speech, but some events might need a closer look, especially if there is potential for major disruption and destruction on campus. School officials, he said, are reviewing their policing tactics, policies and protocols for future events featuring controversial speakers.
The agitators, who keep their faces covered with bandannas, attach themselves to peaceful protests and then break out and start shattering windows and attacking cars, authorities say.
