LOS ANGELES -- Dozens of protesters who heard about a planned Ku Klux Klan rally were waiting by a Southern California park when six Klansmen pulled up in a black SUV and took out signs reading "White Lives Matter." The KKK members were dressed in black shirts decorated with the Klan cross and Confederate flag patches.

The protesters immediately moved in, surrounding the Klansmen. Someone smashed the SUV's window, and then mayhem ensued.

Witness video captured the brawl just after noon Saturday in an Anaheim park about 3 miles from Disneyland. Several protesters could be seen kicking a KKK member. One Klansman with an American flag used the pole's tip to stab a man.

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"I got stabbed," the man screamed, lifting his T-shirt to show a wound to his stomach. A fire hydrant where the man briefly sat was covered in blood.

First responders treat an injured person at a Ku Klux Klan rally and counter-protest Saturday, Feb. 27, 2016 in Anaheim, California. CBS Los Angeles

Officers on scene said they witnessed a Klan member stab a protester with a knife. They found a third counter-protester in a car also stabbed.

The home of Disneyland, the self-proclaimed Happiest Place on Earth, is also the town where the Ku Klux Klan once ran the City Council, patrolled city streets and rallied 10,000 people in a city park.

That rally back in 1924 proved to be a turning point for Anaheim, which ousted the Klan and broke ground on Disneyland a generation later. Now a majority-Hispanic city of 350,000, it's hardly welcome territory for a KKK protest against immigration.

Mayhem ensued Saturday as soon as six Klan members pulled up in a black SUV for the rally they had advertised and pulled out signs saying "White Lives Matter."

By the time ordered was restored, three people had been stabbed, one critically. Twelve total people involved in the brawl were arrested. Five Klansmen were booked for investigation of assault with a deadly weapon, and seven of the approximately 30 counter-protesters were arrested on suspicion of assault with force likely to cause great bodily injury.

CBS Los Angeles reports after reviewing videotape evidence, police released four of the 12 people arrested.

All three people who were stabbed are believed to be counter-protesters.

"I thought they were going to stomp these Klansmen to death," said Brian Levin, who directs California State University, San Bernardino's Center for the Study of Hate and Extremism. Levin, who was monitoring the protest, said he tried to intervene when "all hell broke loose," using his body to get between counter-protesters and Klansmen until officers were able to reach the scene.

Levin said he saw no uniformed officers when the melee started. Sgt. Daron Wyatt said police were definitely there and were engaged with people at one end of the fight, and called for additional resources to deploy to the other end. He said the event stretched along an entire city block.

Police Chief Raul Quezada said his officers were able to respond quickly enough to arrest all but one of the main participants, with the exception of one counter-protester who was still at large Sunday. Four of the arrestees were released after a review of video evidence, he said Sunday in a statement from the city.

"We will always honor free speech in Anaheim, but we vehemently reject hate and violent confrontation," Mayor Tom Tait said added. "Anaheim is proud to draw strength in its diversity, tolerance and kindness, and Saturday's events run counter to that.

A day earlier, Anaheim police had notified the public about the planned protest at Pearson Park and said they would be monitoring the situation. The department also noted that the KKK, like any other group, has a First Amendment right to assemble and demonstrate in a public park.

"Even if the vast majority of our community disagrees with a particular group who visits our city we cannot stop them from lawfully gathering to express their opinions," Quezada said. "Violence is not acceptable, and we will arrest anybody who assaults another person or commits any other crime in our city."

Chris Barker, who identified himself as the imperial wizard of the Loyal White Knights of the Ku Klux Klan, told The Associated Press by phone from North Carolina that his members were holding a peaceful anti-immigration demonstration and acted in self-defense.

"If we're attacked, we will attack back," said Barker, whose organization lists Pelham, N.C., as its headquarters. Last year, the group drew headlines when it protested the removal of the Confederate flag from the South Carolina Capitol.

The KKK has a long history in Anaheim. In the 1920s, several Klansmen held elected office in the city, which was overwhelmingly white but now has a majority of Hispanics among its roughly 350,000 residents.

Nationwide, the number of active KKK groups increased to 190 in 2015 after falling in 2013 and 2014, according to the Southern Poverty Law Center.

In January 2015, packets containing fliers condemning Martin Luther King, Jr. and supporting the Klan were left in the driveways of about 40 homes in Santa Ana, about 8 miles south of Anaheim. The bags contained a KKK business card, rock and candy.

The fliers opened with the heading, "On Martin Luther King Day, you are celebrating a communist pervert." The bottom of the fliers state they came from the "Loyal White Knights of the Ku Klux Klan."

Giovanni Namdar, 25, who runs an auto body shop near Pearson Park, said he saw people speaking passionately on a stage before the violence broke out. He later saw a swarm of police cars and helicopters flood the area.

Namdar said he was stunned to learn about the KKK's presence in the area.

"It's pretty disturbing," he said.