Boston Common will be ground zero for rallies

The heightened concern comes in the aftermath of the Charlottesville rally, where one counterprotester was killed and dozens of people were injured. The violent rally prompted a series of remarks by President Trump that were widely denounced as divisive.

Boston officials said Friday that they will shut down the Saturday event if there are signs of violence.

“The courts have made it abundantly clear that they have the right to gather, no matter how repugnant their views are,” said Mayor Martin J. Walsh. “They don’t have the right to create unsafe conditions. . . . They must respect our city.”

He urged the public not to confront members of hate groups who show up Saturday and advised residents and tourists to avoid the Common during the rally.

“There will be zero tolerance for any violence,” said Police Commissioner William B. Evans. “We’ll have eyes and ears all over that place. We’re not going to let anything happen.”

Evans said several streets around the Common will be closed during the rally, and cameras have been installed in and around the bandstand. Some officers will carry cameras as well.

Evans said his department has ample experience with crowd control, including during the Occupy Boston encampment, Black Lives Matter marches, and sports team championship parades.

But, he said the rhetoric he’s heard leading up to Saturday is concerning.

“I’ve never seen so many people almost looking for confrontation,” Evans said. “Tomorrow’s about coming together against the hate and bigotry.”

Two of the keynote speakers scheduled to address the rally are Kyle Chapman and Joe Biggs.

Chapman gained notoriety earlier this year after he was captured on video smashing a wooden post over the head of an antifascist protester at a march for Trump in Berkeley, Calif. He started the Fraternal Order of Alt Knights, which the Southern Poverty Law Center describes as a “New Alt-Right Fight Club ready for street violence.”

Biggs, a former Army staff sergeant, worked until recently for Infowars, a website founded by Alex Jones, the notorious conspiracy theorist.

Police will seek to keep the rally-goers and the much larger group of counterprotesters separated on Saturday, using officers and barricades between the groups. One group is planning to march from Roxbury to the opposite end of the Common from the rally.

“We’re expecting about 20,000 to 30,000,” Roxbury activist Monica Cannon said. “We’ve had people reach out from the Jewish community, the Asian community. We have people coming from all over the country. I know Black Lives Matter global network, from Toronto, Minneapolis. . . . We have some activists who were on the front lines in Charlottesville coming to Boston as well, so we’re really hopeful.”

Cannon said demonstrators plan to meet in front of the Reggie Lewis Track and Athletic Center in Roxbury at 10 a.m. for the “Fight Supremacy! Boston Counter-Protest & Resistance Rally”. Then they are expected to march down Tremont Street to the Common, at the corner of Beacon and Charles streets.

“We plan to send a really strong message that . . . you don’t get to come here and do this,” Cannon said.

To prepare for the march, dozens of people gathered in the basement of the Union United Methodist Church on Columbus Avenue on Friday for an hours-long training in “nonviolent direct action.” The session was taught by Black Lives Matter activists from Washington, D.C., and activists from New Jersey and Baltimore. It was organized by clergy and activists in Boston.

“You have to think about the actions you’re going to take,” said Tre Murphy, 22, with the Baltimore Black Leadership Organizing Collective, and one of the instructors. “One wrong move can put your life in jeopardy.”

Participants acted out hypothetical hostile situations. Afterward, they discussed how their actions either escalated or deescalated the situation.

Prema Bangera, 31, of Brighton, played the role of a counterprotester who faced raucous “Free Speech” protesters and police.

“I want to make sure I prepare myself mentally, physically, and emotionally,” she said. “I’m preparing for the worst.”

Reverend William B. McClain, senior pastor of the Union United Methodist Church, also participated in the antiviolence training with his wife, Jo Ann, though he was no stranger to facing hate. In September 1963, McClain said, he and another reverend were viciously beaten in Anniston, Ala., when they tried to integrate a library.

After the first black president was elected, McClain said, he thought the country was moving in the right direction. He feels differently now.

“I thought we had a long way to go, but not this far to go,” he said referencing the events in Charlottesville, and Trump’s comments about the protests. “I thought we were closer to a freedom-loving society.”

Others prepared for Saturday by attending an interfaith gathering at Temple Israel of Boston late Friday afternoon. Clergy from various faiths and public officials delivered messages of unity to the more than 1,700 people gathered on the eve of the “Boston Free Speech” rally.

“What unites us is always stronger than what divides us,” said Attorney General Maura Healey.

Healey, a Democrat, also criticized Trump.

“Anyone who struggles to denounce white supremacy or Nazism does not deserve to be president of the United States,” she said, drawing a standing ovation.

“Let’s all go forth . . . as peacemakers,” Governor Charlie Baker told the crowd. Earlier in the day, Baker said that Boston played an important role in the fight for freedom and equality and that that would continue.

“We’re going to do everything we can to make sure tomorrow is about liberty and justice, and about freedom and peace,” he said.

Jan Ransom can be reached at jan.ransom@globe.com. Follow her on Twitter at @Jan_Ransom. Travis Andersen can be reached attravis.andersen@globe.com. Follow him on Twitter @TAGlobe.