This is the first time I've heard of it, but on July 28 there was a clash between a pro-American group and a group of illegal immigration supporters in Fremont (in the East Bay Area in California). From "Protesters may change their tactics":

...Police also said that coalition members were defending themselves when five males, ranging in age from 16 to 28, attacked them...

...The anti-illegal-immigration activists were gathered peacefully at Irvington's Five Corners intersection until Perry's husband, Mike Perry, and four teenage neighbors disrupted them, police said. They struck coalition members, some of whom were elderly, and knocked signs out of their hands, police Detective Bill Veteran said.

"I saw the whole thing unfold," he said.

Mike Perry, 28, said he was arrested on an outstanding warrant related to an unresolved traffic violation. Two minors — ages 16 and 17 — and 18-year-old Tony Rounds also were arrested Friday on suspicion of battery, police said. David Anaya, 18, was arrested on suspicion of assaulting a police officer.

Police said that all four of the teens taken into custody have gang affiliations.

"One of them admitted it to us, and we have them on videotape flashing gang signs," Mazzone said. But Priscilla Perry emphatically denied that she, her husband or the four teens have any gang ties...

The pro-American group has been hounded by counter-protesters from the International Socialist Organization; most of them were apparently on their way to the corner where the fight occured and they claim that the attackers are not affiliated with that group. However, from this report:

Fremont police Detective Bill Veteran, who witnessed the scene, said a small group of pro-immigrant Fremont teens started the trouble, egged on by chants from ISO members.

In the first report, the ISO shows how much they respect the First Amendment:

Meanwhile, leaders of the International Socialist Organization, who support granting citizenship to the nation's 12 million illegal immigrants, disagreed. They painted a contrasting picture of Friday's events, blaming coalition members for starting the violence.

"You don't go to a community as diverse as Fremont and say, 'Immigrants go home' and 'Build a fence on the border,' unless you're looking for a fight," [spokesman Michael Smith] said.

They're now working on a legal defense with the National Lawyers Guild.

While the above reports are somewhat balanced, if the MSM's dreams had come true and pro-borders groups had attacked helpless "immigrants" we would never hear the end of it. This incident will obviously not be endlessly discussed. It's odd how the news media supports groups such as the ISO that clearly do not believe in the Constitutional protections that they require to do their jobs.