Violence in Charlottesville, Virginia, set Americans on edge over the weekend as officials in Boston cast a wary eye on a rally planned for Boston Common this Saturday.

In a letter Monday, anti-racism groups called upon Boston Mayor Marty Walsh to develop a public safety plan to address Saturday's rally and sought an "emergency meeting" with the mayor.

"Any violence that erupts in the Boston Common or on the busy city streets would directly affect the heart of the city, including the downtown residential and commercial core," read Monday's letter from the Lawyers' Committee for Civil Rights and Economic Justice, the Anti-Defamation League, the Massachusetts Association of Minority Law Enforcement Officers and others. The letter said, "Violence could easily spread city-wide."

The Boston Herald reported that the rally organizers have not pulled permits for their event, and that Walsh does not want them in Boston.

Information about who is behind Saturday's event - billed as The Second Boston Free Speech Rally - is in some dispute. Brian Fallon, a former spokesman for Hillary Clinton, said the group that rallied in Charlottesville is planning the noon event on Boston Common. On Facebook, the group Boston Free Speech denied association with the Unite The Right group involved in the Virginia rally that led to violent confrontations.

"We are not in any way associated with the organizers of the Charlottesville rally," the group posted to Facebook. The post continued, "There has been threats made against our lives already and we will be contacting Boston PD."

Virginia Gov. Terry McAuliffe told National Public Radio Monday the Unite the Right ralliers were "disgusting human beings" and said they "felt emboldened" when they arrived armed in Charlottesville. Some were wearing helmets and body armor, he said, and others had semi-automatic rifles.

"You should have heard the language in what these people said on the streets, yelling at the African American community, yelling at members of the Jewish faith," McAuliffe said. "I've been doing this a long time - 40 years - I never in my life have seen such vicious, mean-spirited hatred. And that's why I said, 'Get the heck out of here.' I don't know who these people are."

In Charlottesville, groups reportedly clashed over plans for the city to remove a statue of Robert Lee, the Confederate general who surrendered to the United States Army in Appomattox, Virginia, ending the Civil War.

In addition to the brawling in Charlottesville, an Ohio man allegedly slammed his car into people and another car, killing Heather Heyer, who had been protesting the white nationalists rallying in the city, and injuring many others. McAuliffe called the suspect a "car terrorist."

There appears to be some connection between the Charlottesville group and the planned protest in Boston. The Boston group wrote on Facebook, "Hope anyone who was in Charlottesville today made it out safe. We have confirmed Baked Alaska will be attending our rally next week."

Baked Alaska is an alt-right provocateur named Tim Gionet, who reported on Twitter that he was pepper-sprayed in Charlottesville.

"You can kick & scream all you want - but you won't stop our free speech, you won't stop our ideas. We are winning. #Charlottesville," Gionet wrote on Twitter.

Newton Mayor Setti Warren, a Democrat who is running for governor next year, advised people not to react to Saturday's violence by pushing "people back into their partisan corners."

"My grandfather fought the Nazis in the Battle of the Bulge. I will fight to stop the spread of their evil ideology today if I have to, but I will not allow the anger I feel about the evil actions of a despicable few to drive me to hate my fellow Americans with whom I have political disagreements," Warren said in a statement. "This is a serious challenge for our nation, but it is not about Democrats versus Republicans. It is about good versus evil, love versus hate, the best of America versus Nazis."

McAuliffe, speaking with NPR's David Greene, said public officials need to speak up against white supremacists.

"Elected officials need to come out number one and condemn - call it for what it is, these were white supremacists, they were neo-Nazi. They came into our beautiful state, our beautiful city with their hate and their bigotry and I told them to get out. You know, they're not wanted here. But let's be honest Dave, they're not wanted anywhere in America," McAuliffe said.

Gov. Charlie Baker tweeted Saturday evening, "E Pluribus Unum - out of many, one. This is who we've been & who we must be. Hatred & bigotry have no place here."

"Public safety is the top priority of the Baker-Polito Administration and state officials are in touch with Boston law enforcement to monitor the situation and ensure everyone's safety," a spokesman for Gov. Charlie Baker said in a statement. "Governor Baker is saddened and disturbed by the tragic events in Charlottesville, and believes hatred, bigotry and violence as well as those who promote it have no place in our Commonwealth or country."

Michael P. Norton contributed reporting.