WASHINGTON — A right-wing rally at Freedom Plaza in downtown Washington on Saturday led to skirmishes with counterprotesters as a massive contingent of District of Columbia police worked to maintain order.

Black-clad antifascists, known as antifa, briefly marched along city streets, and police repelled their attempts to erect a barricade with newspaper boxes and chairs. Police had earlier broken up a clash between that group and the Proud Boys, a self-proclaimed Western-chauvinist fraternal organization that promotes ending welfare and closing the borders.

Up until then, the rally by the Proud Boys and other groups to protest being blocked on social media had been relatively peaceful. There were a few tense exchanges with participants organized under the banner of “All Out D.C.,” who gathered in adjacent Pershing Park to drown out what they decry as “the face of white nationalism and supremacy.”

The two sides were kept apart by police and barricades on 14th Street NW, which separates the two parks near the White House. But around 12:30 p.m., a group of hooded antifa protesters skirted police lines, reached a corner near Freedom Plaza and surrounded a man wearing a “Make America great again” hat. Police grabbed the man amid the scuffle and pulled him to safety. Antifa demonstrators then marched along several streets, only to mass again at 14th and F streets, before returning to Pershing Park.

District Police Chief Peter Newsham said no arrests were made, but he sent extra officers to block off other streets.

Even as police worked to keep the two sides apart, authorities worried what might happen when the rally ends at 3 p.m. and people disperse. The counterprotesters vastly outnumbered those in Freedom Plaza.

At one point, police expanded the separation zone on 14th Street so people on either side could not hear each other yelling across. Many streets were blocked off with large trucks.

Authorities were trying to avoid a repeat of last month’s bloody street brawls in Portland, Oregon, between the Proud Boys and antifa protesters, whom police blame for violence and destruction during President Trump’s inauguration on Jan. 20, 2017.

The confrontation at Freedom Plaza occurred as Gavin McInnes, founder of the Proud Boys, took the stage, followed by right-wing journalist Laura Loomer and Milo Yiannopoulos, an incendiary writer who helped make Breitbart News a leading platform for the alt-right.

Yiannopoulos appeared dressed in drag, with a black pixie wig and fake breasts beneath a blue T-shirt. The crowd applauded loudly as he extolled the virtues of Christianity and the nuclear family and attacked mainstream journalists, left-wing activists and “Vichy conservatives” he said were not courageous enough to act on their principles.

“The left must be made to fear you,” Yiannopoulos said, occasionally pausing during his speech to adjust his wig and fake bust. “Massive brutal retaliation for the slightest of perceived insults must be the way from now on. . . . If they tear down your idols, burn down their cathedrals.”

Shortly before 1:30 p.m., Yiannopoulos was escorted out the back of the rally by several Proud Boys. Police officers opened a barrier for him to pass through, trying to avoid reporters and photographers.

Organizers of both rallies had said they were not looking to instigate violence but were ready to respond. Authorities said they were ready as well.

The day started with yelling but no physical violence.

Proud Boys in their trademark black-and-yellow polo shirts – as well as several people in red MAGA hats and some clad in both – gathered at their side of the blockade to yell at a scattering of counterprotesters on the other side.

But the police cordon had done its job. No one on the other side could hear a word of what they were saying

“What was that?” counterprotesters asked one another.

Earlier in the morning, the two groups had more direct contact, with participants trading cries of “why are you here?” across the police divide in Pershing Park.

A counterprotester began a heated debate with a small group of Proud Boys and their supporters on Freedom Plaza.

Rick Ferran, one of the scheduled speakers at the Demand Free Speech rally at Freedom Plaza, said his organization, Uncle Sam’s Misguided Children, has repeatedly been kicked off Facebook. He interrupted the dispute with a jeremiad against socialism and communism. A Cuban immigrant with a shaved head, Ferran was sweating profusely as the July sun beat down.

“If we do not attack the cancer that is destroying our freedoms in this country, we will dissolve,” he declared.

NeeNee Taylor, an organizer for Black Lives Matter D.C., exhorted the Pershing Park crowd to remain nonviolent.

“We’re not here for violence,” she told her audience, which included members of the immigrant rights group Sanctuary DMV and the anti-gentrification organization Keep D.C. 4 Me. “We’re here to celebrate black and brown and marginalized people.”

The right-wing groups gathered under a banner reading, “Demand Free Speech,” in the last of three rallies – the first two were in New York and San Francisco – meant to address a wave of social media companies banning right-wing figures from their platforms.

Proud Boys leader and event organizer Luke Rohlfing told the Daily Beast that the event is also aimed at left-wing anti-fascist activists after the violent clash in Portland last week left conservative writer Andy Ngo bloodied, shaken and doused in a vegan milkshake.

The rally was being held two days after Trump’s July 4 “Salute to America,” which featured added fireworks, a presidential speech and a show of military vehicles, tanks and airplane flyovers.

Fears of violence between Trump supporters and critics did not materialize, though there were some minor clashes on the Mall and a fight outside the White House after a member of a communist group set two American flags on fire on Pennsylvania Avenue.