A police officer grabs a man antagonizing "anti-fascist" protestors after multiple people were stabbed during a clash between neo-Nazis holding a permitted rally and counter-protestors on Sunday at the state capitol in Sacramento, California, United States, June 26, 2016. [Photo/Agencies]

June 26 - At least 10 people were injured at a rally outside the California state capitol in Sacramento on Sunday as members of a white supremacist group clashed with counter-protesters, authorities said.

The melee erupted during a rally staged by the Traditionalist Worker Party, described by the Southern Poverty Law Center as a white nationalist extremist group.

One of its leaders, Matt Parrott, said the party had called the demonstration in part to protest against violence that has broken out outside recent rallies by Donald Trump, the presumptive Republican presidential nominee.

The incident may fuel concerns about the potential for violent protests outside the major party conventions in Cleveland and Philadelphia this summer and in the run-up to the Nov. 8 presidential election.

"With the eyes of the world's media on both Philadelphia and Cleveland, no doubt there will be significant protests," said Democratic strategist Steve Schale. "The extreme rhetoric, combined with the nonstop media attention, does encourage these kinds of events."

In Sacramento, when the white supremacists arrived at the capitol building at about noon on Sunday, "counter-protesters immediately ran in - hundreds of people - and they engaged in a fight," said George Granada, a spokesman for the Capitol Protection Service division of the California Highway Patrol.

In announcing the counter-protest, a group called Anti-Fascist Action Sacramento said on its website that it had a "moral duty" to deny a platform for "Nazis from all over the West Coast" to voice their views.

"We have a right to self defense. That is why we have to shut them down," Yvette Felarca, a counter-protester wearing a white bandage on her head, told reporters after the clash.