Loren Taylor knew it was going to be a bruising campaign when he set out to unseat Oakland City Councilwoman Desley Brooks in this year’s election.

Still, the 40-year-old business consultant and third-generation Oaklander didn’t anticipate being threatened with physical violence while campaigning. But, that’s what he says happened last weekend.

Here’s the story of how a first-time council candidate and his campaign volunteers were chased from a city event in East Oakland by security guards in what is shaping up to be a tense election season in Oakland. The incident was witnessed by several people, and two District Six residents reached out to tell me how disturbing it was.

Brooks, who’s held an iron grip on District Six for 16 years, acknowledged that Taylor (no relation to me) was at the event but said she was unaware of Taylor’s interaction with people in the park, including security guards.

At around 12:30 p.m. Saturday afternoon, under trees in Arroyo Viejo Park, Taylor pitched a canopy and set up blankets and chairs in the grass, just like dozens of other people attending the city event promoted by Brooks and others as a community picnic. The free event used city funds, and booths there included the Oakland Fire Department and Alameda County Registrar of Voters.

The picnic was for Juneteenth, which commemorates the emancipation of slaves in Texas on June 19, 1865 — two months after the Confederate army surrendered, ending the Civil War, and three years after the Emancipation Proclamation.

Taylor said he taped his campaign poster boards to the poles of the canopy. He was joined by nine volunteers, including high school students and retired district residents, to hand out campaign fliers.

According to Taylor, Brooks walked by, saw what he was doing and stopped in her tracks.

Taylor said Brooks told him she couldn’t believe he was campaigning there — that he wasn’t allowed to and that he needed to take his signs down. He said she did not explain why it wasn’t allowed but took a photo and told Taylor she’d file an ethics complaint.

In an email days later, Brooks told me Taylor was violating a rule that prohibits city resources from being used to campaign for or against candidates and ballot measures.

Taylor told me he didn’t want to be confrontational with Brooks, but he wanted to hold his ground because he felt he wasn’t doing anything wrong. He offered to take the poster boards down, as requested. He said Brooks walked away without responding.

Taylor said he was chatting with attendees when security guards approached. He said they told him it was a private event and that Taylor had to leave. Taylor protested, pointing out that it was a free public event.

Taylor said the security guard told him that Brooks wanted him out of there — and that if he had an issue with that, he’d have to talk to Brooks about it.

Taylor asked to speak to Brooks.

He said she didn’t come back, but a man who said he was the head of security did. And he brought help.

That’s when a sunny day in the park got tense.

Taylor recalled the head of security telling him that he was going to pick up his stuff and walk it outside the park — and if Taylor got in the way, they’d pick him up and put him out of the park, too.

The security guards, some wearing jeans and T-shirts and two in the leather vests of a motorcycle club, collapsed the canopy, and stood nearby to make sure Taylor didn’t put it back up, Taylor said.

Taylor put the canopy in a car and returned to the park with three volunteers. Some volunteers, fearing physical harm, didn’t return to the park. He had his campaign flyers in a bag slung across his chest, a “Loren Taylor for Oakland” sticker on his breast.

From the stage, there were repeated announcements that political campaigning wasn’t allowed at the event. According to Taylor, there was also repeated praise for Brooks from the stage.

As Taylor walked around, he saw people wearing T-shirts with Brooks’ name on them filming him. By then, he’d stopped handing out flyers. Still, a security guard approached Taylor and said people were complaining that he was handing out campaign flyers.

Taylor heard another security guard say that if he saw Taylor and the volunteers passing out material, he was going to slap it out of their hands.

Less than two hours after he began setting up for the afternoon, Taylor decided to leave the park.

“The real issue (was) our presence,” Taylor told me a few days later in Cafe Teatro, the coffee shop on the east side of Frank H. Ogawa Plaza in downtown Oakland where he was prepping to pitch himself to a local union. “It’s the fact that we’re actually showing up in East Oakland to be part of the community that we hope to serve when I get into office.”

I reached out to Brooks for her side of the story, letting her know what Taylor said happened. She didn’t respond to details of her interaction with him. Instead, in an email, she wrote: “I am not aware of Loren Taylor’s interaction with other people. Typically security hired for city events are aware of rules that prohibit campaigning. I will ask around but have not heard about any ‘threatening’ incidents at this event.”

She offered the ethics law she believes Taylor violated.

Sure, Taylor crashed Brooks’ party. But was it a violation of campaign ethics?

Whitney Barazoto, executive director of the Oakland Public Ethics Commission, declined to weigh in because the commission hasn’t performed an analysis. And it won’t unless a complaint is filed.

Brooks didn’t respond when I asked if she filed a complaint or was planning to.

“I can’t make any comments on specific scenarios or hypotheticals,” Barazoto said. “We need to be able to have all of the facts of a particular situation.”

I asked Mark Morodomi, a former deputy city attorney for Oakland, this question: Can a candidate for office campaign at a city-sponsored event in a public park?

“That’s a pretty simple question,” Morodomi said. “A candidate for city office has the same First Amendment rights that anybody else would at a city park at a city-sponsored event. They can do whatever any other citizen could.”

In other words, Taylor had pitched his canopy on solid ethical ground. He shouldn’t have been made to stop campaigning. Brooks did not respond when told of Morodomi’s opinion.

Taylor, meanwhile, has asked the Oakland Public Ethics Commission for clarification on whether there are restrictions on campaigning at a free public event.

“The whole reason I decided to jump into this is to give back to Oakland at this critical time so we do go in the right direction,” he said.

Buckle up, because it’s going to be a bumpy ride.

San Francisco Chronicle columnist Otis R. Taylor Jr. usually appears Mondays and Thursdays. Email: otaylor@sfchronicle.com Twitter: @otisrtaylorjr