A woman described as the main organizer of a Black Lives Matter march in California was arrested Tuesday as the event was winding down, according to reports.

The woman reportedly taken into custody was identified as Tianna Arata. She was apprehended and placed inside a police vehicle in San Luis Obispo as other protesters were loading their placards and other items into a car, the Tribune of San Luis Obispo reported.

San Luis Obispo is the seat of San Luis Obispo County, located about 189 miles up the Pacific coast from Los Angeles.

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Witnesses said Arata complied with police peacefully, the Tribune reported. They said police officers told them she was being arrested for allegedly inciting a riot.

Several protesters then traveled to the county jail to demand that Arata be freed, according to the newspaper.

Earlier in the evening, county District Attorney Dan Dow posted a “public safety alert” on Twitter because a group of some 300 protesters had blocked Highway 101.

“This is unlawful and dangerous,” Dow wrote. “It must stop.”

Hundreds of vehicles were delayed as protesters marched along a stretch of the highway, the newspaper reported.

Glass smashed onto child

Some protesters damaged the hood of a car and smashed a rear window of a vehicle, sending glass fragments all over a 4-year-old child who was seated inside, KEYT-TV of Santa Barbara reported. It was unclear if the child was injured.

At one point in the evening, a woman who opposed the protest began yelling at the crowd.

Tuesday’s protest was prompted in part by comments made at a local Tea Party event earlier this month by San Luis Obispo County Sheriff Ian Parkinson, the Tribune reported.

“I said the only thing I know about prejudice is when I put on a uniform and somebody doesn’t like me because I’m wearing a uniform,” Parkinson said in a video. “I do understand in areas that have heavy minority communities, how they might feel that way, but here in San Luis Obispo, we’re being trashed by this issue of something that truly is not here in that form.”

“Racism is everywhere,” the sheriff told the Tribune, but said he’s “never seen any indication that systemic racism exists in this county.”

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San Luis Obispo Mayor Heidi Harmon attended Tuesday’s protest and told the newspaper that minorities often “feel very uncomfortable and unwelcome” in the predominantly White area, and many residents were hoping to change that.

“I think that those of us that are White and have the privilege of all of that don’t understand how sort of alone and unconnected people feel," she said.