Violence erupted at a Make America Great Again rally at Bolsa Chica State Beach in Huntington Beach on Saturday, video and photos from the scene showed.
The fights started about an hour into the demonstration leading to the arrest of four people. Three were arrested in connection with illegal use of pepper spray and one person was arrested on suspicion of assault, according to the Huntington Beach Police Department.
A counter-protester who was wearing a black mask, allegedly pepper-sprayed a woman and one of the organizers of the event after being hit, apparently sparking the violence.
"That guy over there walked up and pepper-sprayed my wife from two feet away who's a non-violent walker out here to be proud of our country," said Travis Guenther, a Trump supporter. "You want to have punks like this come up. What's more American us out here displaying our freedom of speech rights, or that little punk over there spraying people in the face with mace."
Punches were thrown while people scuffled in the sand while holding mega phones and flags, video showed. Demonstrators chanted "USA" and "America First" as the crowd grew.
"It's unreal. It's unreal. I wasn't expecting anything," said Steele Vaz, a Trump supporter. "I was trying to stop things, trying to keep the peace, but they just started spraying and hitting."
The man in the mask was then tackled by a group of Trump supporters and he was punched and kicked, the Los Angeles Times reported.
"This guy assaulted him too with a flag like that," said Naui Huitzilopochitli, a Trump protestor, referring to a man who allegedly hit a protestor with a Make America Great Again flag pole. "That's why his face is bloody. I saw white supremacists there. These guys were yelling 'white power' while they were hitting him."
At one point counter-protestors surrounded one of the leaders and asked him about his thoughts on the violent clashes, video showed.
Officers confiscated a number of weapons, including a steel hammer and a tire iron, after the fights subsided.
The rally comes a day after the Republican health care bill was pulled from the House floor when it failed to get votes.
The event was expected to run from noon to 3 p.m. and is one of about 40 affiliated events scheduled nationwide throughout the day, according to the Times.
Many demonstrators dispersed after the incident subsided.