Richard Pan, a California state senator who has been leading a charge to tighten the state’s immunization laws, was heading to lunch on Wednesday when a man accosted him.

“Oh my goodness, you guys, what are the chances of this?” Austin Bennett, an anti-vaccine activist and conspiracy theorist, asked his 4,500 Facebook followers. The 54-year-old had been live-streaming his walk through downtown Sacramento, railing against the CIA and supposed chemtrails. Then he spotted Pan, the Democrat he previously tried to supplant in the state Senate and this year launched a petition to recall.

For years, Pan, a pediatrician, has been a target of anti-vaccine activists. After a 2015 measles outbreak at Disneyland, he authored legislation that barred parents from opting out of vaccinating their school-age children on account of their personal beliefs. This year, as California saw a surge in parents claiming medical exemptions for vaccinations, Pan introduced a bill that would give public health officials more oversight. He has experienced his fair share of online vitriol, screaming protesters and death threats.

But the Democratic lawmaker had never been the target of physical violence — until Bennett shoved him from behind, sending him stumbling down the sidewalk.

“I get harassed on social media, practically daily,” Pan told KQED on Wednesday afternoon. “We’ve got to tone down the rhetoric. Assaulting a public official is the next logical outcome of violence-inciting language.”

Bennett, who live-streamed the unprovoked attack on Facebook, was cited with misdemeanor battery on Wednesday and released, Sacramento Police Department Sgt. Vance Chandler said in an email to The Washington Post.

In the video, Bennett follows the California politician down the street and aggressively peppers him with questions, citing debunked claims that vaccines contain dangerous metals. Pan, smiling, pushes back against the line of questioning and suggests that Bennett study public health. After several minutes of back-and-forth, Pan turns to the lawmaker walking beside him, chuckling and commenting, “Oh, boy."

Then, Bennett comes up behind him and gives him a hard shove.

“Yeah, I pushed you,” Bennett says, as the lawmaker regains his balance. “I pushed you. I pushed you. Adios.”

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Moments later, Bennett admits, “I probably shouldn’t have done that.” But he keeps following Pan, haranguing him about vaccines until the lawmaker takes cover inside a restaurant.

“If he got what he deserved, he would be hanged for treason for assaulting children, for misrepresenting the truth,” Bennett says on the video.

California Assemblyman Ash Kalra, the Democrat who was walking alongside Pan while the video was filmed, told Fox 40 that the footage didn’t fully capture how tense the situation became.

“The video doesn’t do it justice, as to how dramatic it was at that moment in time. It was a hard shove,” he said. “At first, I thought it was a punch. The sound of the impact was really loud. And if you look at the video, you can see Dr. Pan kind of like going forward quite a few steps ahead of me and that was the force of the push.”

Although the Democratic lawmaker wasn’t injured and went on to chair a committee hearing after the incident, the confrontation left many feeling on edge. Speaking to the Los Angeles Times, Pan’s spokeswoman, Shannan Velayas said skepticism about vaccines was “moving from peculiar fringe curiosity to a violent extremist movement."

Bennett didn’t respond to a request for comment on Wednesday but spent several hours live-streaming on Facebook after he was released by police. Though he admitted guilt and said that he was not going to make excuses for his behavior, he also accused Pan of being part of a “cabal” that was “poisoning the minds of our children” with vaccines and wrote that he did not owe the lawmaker an apology.

The activist — who said in his video that he had been angry that Pan seemed to have laughed at his questions — has made multiple attempts to unseat the state senator. According to the Times, he unsuccessfully challenged Pan in a 2018 Democratic primary and this year filed a recall petition alleging that the lawmaker was committing treason by trying to tighten vaccination requirements.

On Wednesday, Pan told KQED that Bennett had verbally harassed him on previous occasions, confronting him at the state capitol and elsewhere in his district, which covers a large portion of the Sacramento area.

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Pan isn’t the only California lawmaker facing hostility and harassment for his support of vaccines. According to the Sacramento Bee, the bill that he introduced to limit medical exemptions has drawn hundreds of protesters to the state capitol, and its sponsors have been getting death threats for months. While proponents say the measure is necessary to prevent parents from shopping around for doctors who will grant exemptions to children who have no medical need to avoid vaccines, activists say that it interferes with the doctor-patient relationship.

“It should not come as a surprise to anyone that violence is the natural next step of this extremist movement that has used inciting language for a long time,” Velayas told the paper. “We must take this threat seriously because what is next? The next time, they could use a knife or gun.”