California official says she was stalked by members of an anti-vaccine group.

The president of California’s medical board was “followed and confronted” in a dark parking garage in the city of Walnut Creek by a group that promotes misinformation about the coronavirus pandemic, she wrote on social media this week.

Kristina D. Lawson, who is an appointee of former Gov. Jerry Brown and has served on the board for six years, was the target of a group called America’s Frontline Doctors, a spokesman for Ms. Lawson said on Friday.

The group, which did not immediately respond to a message from a reporter, has shared debunked and misleading claims about the virus, including that hydroxychloroquine was an effective coronavirus treatment and that masks did not slow the spread of Covid-19.

The group’s videos have been promoted on Twitter by former President Donald J. Trump and have spread through Facebook groups dedicated to anti-vaccination movements and conspiracy theories such as QAnon, racking up tens of millions of views.

Ms. Lawson’s account comes as public officials across the country, including school board members, have faced vitriolic backlash from parents and others who are opposed to pandemic mandates.

Ms. Lawson said on Twitter that she was concerned on Monday morning when she saw someone flying a drone over her house and saw a white vehicle parked outside. That evening, when she left the law firm where she works, her concern turned to terror, she said.

Four men hopped out of the white S.U.V. with cameras and recording equipment and confronted her as she tried to get into her car, she said. Her spokesman said they announced themselves to her as being with America’s Frontline Doctors, and they had the group’s logos on their jackets and microphones.

In her Twitter thread, Ms. Lawson said that members of the group, when contacted by law enforcement, had indicated they just wanted to interview her for a video they were producing. Ms. Lawson said that the group never contacted her for an interview.

“Instead, they ambushed me in a dark parking garage when they suspected I would be alone,” she wrote.

In a statement, Ms. Lawson, a former mayor of Walnut Creek, which is in the Bay Area about 15 miles east of Oakland, described herself as the daughter of a physician who believes in robust public dialogue but that the group’s behavior is “beyond the pale.”

“As a mother, I felt deeply violated and scared for my kids in our own home — and I feared for my own personal safety as a woman being surrounded by strange men in a dark parking garage,” she said.

The police said they were looking into a man who had called the department earlier in the day, claiming to be a “state detective” from Georgia who was “conducting surveillance” in the area.

Lt. Holley Connors, a spokeswoman for the Walnut Creek Police Department, said investigators believe the man was “likely involved” in the incident involving Ms. Lawson.

“At this time, there is no evidence of a crime,” she said, “but the Walnut Creek Police Department will continue to follow up on the incident.”