Hundreds of demonstrators from the left and the right gathered at UC Berkeley on Thursday night amid a heavy police presence as conservative commentator Ben Shapiro, a former Breitbart editor, made a speech on campus.
Berkeley police, clad in riot gear, made at least three arrests before the Shapiro event started at 7 p.m. More arrests were reported after the event. Later Thursday night, Berkeley police put the total number arrested at nine. The university spent $600,000 to enhance security measures during the closely-watched event.
Police identified five of the people arrested. Sarah Roark, 44, of San Francisco; Hannah Benjamin, 20, of Fremont; Eddy Robinson, 44, of Oakland and Michael Paul Sullivan, 29, of Hayward were arrested for carrying banned weapons, police said. And Kerem Celik, 18, of Saratoga, was arrested for disturbing the peace.
While Shapiro was still speaking inside Zellerbach Hall, demonstrators began marching down Bancroft Avenue, and tensions began to rise. Immediately after Shapiro finished his speech and a lengthy question-and-answer session, the crowd filling the street remained peaceful.
Later, one woman was injured in a scuffle over a sign and had to be taken away by ambulance.
The university had sealed off large parts of its campus like a fortress, with a closed perimeter and a "very large" visible police presence Thursday, when the birthplace of America's free speech movement faced its next potential clash.
City and campus authorities anticipated the demonstrations and prepared for possible violence with a variety of new strategies and tightened security.
For the first time in two decades, Berkeley officers were armed with pepper spray, after the City Council modified a 1997 ban at an emergency meeting this week.
The tactics to boost security are the latest indication of growing frustrations in Berkeley and other liberal cities that have become targets of violent political protests since the election of President Donald Trump and battlegrounds for extremist groups that support and oppose him.
"We have seen extremists on the left and right in our city," said Berkeley Mayor Jesse Arreguin, a Democrat who backed the police request to use pepper spray. "We need to make sure violence is not allowed."
Berkeley business owners, meanwhile, were preparing for the worst-case scenario by boarding up their properties to avoid a repeat of the damage caused when Milo Yannopoulis was scheduled to speak in February.
“Today is really about free speech,” said Berkeley business owner, Luis Medina, who was boarding up several Bank of America ATM’s on Telegraph Avenue. “We’re just trying to protect the property as much as we can.”
The university mandated stores that could be affected by protesters to close their doors by 3:30 p.m.
Shapiro's event, organized by campus Republicans, was being watched as a warm-up act for later this month when provocative, right-wing speaker Yiannopoulos says he plans to hold a Free Speech Week on Berkeley's campus with a 20-person lineup that includes Ann Coulter and Steve Bannon, Trump's ex-chief strategist and head of Breitbart News. Campus officials say the event is not yet confirmed.
It will be Yiannopoulos' second attempt to speak at Berkeley this year, after an event in February was abruptly canceled when masked, hooded left-wing anarchists dressed in black rioted outside the event, setting fires and smashing windows on campus and on nearby city streets.
Police and UC Berkeley officials were criticized at the time for giving demonstrators wide latitude and standing aside as the masked anarchists hurled Molotov cocktails at officers and caused $100,000 worth of damage.
Violence escalated at subsequent off-campus protests and authorities say they have learned hard lessons as they struggle to balance free speech rights with preventing violence.
Yiannopoulos posted on his Facebook page that he intends to bring along 16 Navy SEALs to his Berkeley appearance later this month.
UC Berkeley's Provost Paul Alivisatos sent a recent campus-wide message detailing security plans, saying no one wearing masks or carrying weapons of any sort will be allowed on campus.
A similar event featuring Shapiro on campus in 2016 before Trump was elected and also hosted by Berkeley College Republicans had "basic security." It went off peacefully and made no major headlines.
Berkeley's frustrations are shared by officials in other famously liberal cities such as Seattle and Portland, Oregon, where Trump supporters and left-wing protesters have repeatedly taken to the streets in supposed free speech demonstrations that have resulted in violence.
At a protest last week in Portland, police said anti-fascist protesters threw smoke devices and other projectiles at officers trying to keep the peace between pro- and anti-Trump crowds. Seven people were arrested.
Black-clad protesters have been a menacing presence at protests in the Pacific Northwest since before Trump was elected, often clashing with police at May Day marches, and they continue to show up at the many demonstrations.
Greenwood, the Berkeley city police chief, sought permission for police to use pepper spray because he said it is preferable to batons and tear gas for crowd control. Tear gas when fired disperses much more widely than pepper spray, raising the risk of hurting peaceful protesters who may be near violent demonstrators, Greenwood said.
"It is a request made of urgency," Greenwood told the City Council, calling protecting protesters and police amid continued violence in the city "a unique problem."
He added: "The scope and scale of these demonstrations in our community is unprecedented."
NBC Bay Area's Jodi Hernandez and Sam Brock contributed to this report.