One Anaheim police sergeant saw another Klan member with a knife in his hand and a counterprotester bleeding nearby, Wyatt said. The sergeant took the KKK member into custody. Meanwhile, counterprotesters stomped on two KKK members, he said.
"All hell broke loose," said Brian Levin, director of California State University, San Bernardino's Center for the Study of Hate and Extremism, who witnessed the violence. "I thought they were going to stomp these Klansmen to death."
Wyatt said police were present when the violence erupted, but he did not say how many officers were deployed.
Anaheim police had notified the public about the planned KKK protest Friday and said they would be "monitoring the situation for any violations of law." The department also said that while the group's signs and fliers might be provocative, they are protected by the First Amendment.
Levin said he did not see any uniformed officers at the park when the violence erupted. He said he tried to get between counterprotesters and Klansmen to help quell the melee until officers were able to reach the scene.
"I'm still kind of a little bit shaken by it," he said.
Police Chief Raul Quezada defended the way his department handled the situation, saying a contingent of officers were dedicated to the gatherings and they were able to arrest all of the main participants in the clash.
"Preventing violent confrontations is always our goal; unfortunately the handful of individuals committed to criminal behavior this afternoon caused the violent episode," he said in a statement.
Chris Barker, who identified himself as the "imperial wizard" of the Loyal White Knights of the Ku Klux Klan, said his members were holding a peaceful anti-immigration demonstration and acted in self-defense.
"If we're attacked we will attack back," said Barker, who did not attend the rally and spoke by phone from North Carolina. The 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.
Among tHose taken into custody were six Klansmen, who were booked for investigation of assault with a deadly weapon, and seven counterprotesters.
Anaheim police said all three of the stabbing victims were in stable condition.
The KKK has a long history in Anaheim. In the 1920s some Klansmen held elected office in the city, which was overwhelmingly white but now has a majority of Hispanics among its roughly 350,000 residents.
In January 2015, packets containing fliers condemning the Rev. Martin Luther King Jr. and supporting the Ku Klux Klan were left in the driveways of about 40 homes in Santa Ana, about 8 miles south of Anaheim. The fliers opened with the heading "On Martin Luther King Day, you are celebrating a communist pervert." The bottom of the fliers stated they came from the "Loyal White Knights of the Ku Klux Klan."
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, which tracks hate groups.
Associated Press reporter Daisy Nguyen contributed to this report.
