A wild conspiracy theory shut down a festival that was supposed to take place Saturday in the foothills of the Sierra to raise money for a charter school.

It started with a tweet from former FBI director James Comey.

#FiveJobsIveHad 1. Grocery store clerk

2. Vocal soloist for church weddings

3. Chemist

4. Strike-replacement high school teacher

5. FBI Director, interrupted — James Comey (@Comey) April 27, 2019

The seemingly innocuous hashtag #FiveJobsIveHad was interpreted by some conspiracy-minded individuals to be a reference to Jihad. Next, the internet sleuths took the first letter of each item to reach the acronym GVCSF.

A quick internet search led the collection of Twitter trolls to the Grass Valley Charter School Foundation, whose annual Blue Marble Jubilee was scheduled for this weekend.

Several Twitter users floated the notion that Comey’s post was a “coded false flag message” describing the festival as a target.

“Nothing better happen” at the fundraiser, said one user, who connected the time stamp on Comey’s tweet to when a plane hit the World Trade Center during the 9/11 terror attacks. The bizarre post quickly racked up nearly 2,000 retweets.

Some of the Twitter users appeared to be followers of Q, or QAnon, the long-debunked, far-right conspiracy theory that President Trump and Special Counsel Robert Mueller will work together to take down Trump’s political enemies who allegedly engage in pedophilia and other crime.

Several people, apparently concerned after reading the theory on the jubilee fundraiser, called and emailed the school as well as local law enforcement to warn them, said Sgt. Brian Blakemore, of the Grass Valley Police Department. The callers sounded coherent — “not the tin foil hat in the dungeon type that you might expect,” he said.

“The school became aware when these followers of this conspiracy theory guy started contacting the school and the Police Department, letting us know there was this plot that was being uncovered and that we had to be sure to protect the kids and the site,” he said. “The school never received a direct threat; it was people warning them about this plot.”

In addition to the school, foundation and police, Nevada County sheriff’s deputies and FBI agents in the Chico field office were contacted about the alleged attack planned for the festival.

Blakemore said the idea of an attack was baseless.

Local officials and school leaders were not concerned about a terror plot, but rather that concerned citizens “might show up to guard the place,” he added.

If a vigilante made an appearance, it wouldn’t be without precedent.

In 2016, the false Pizzagate conspiracy theory, which claimed Democrats were running a child sex ring in a Washington pizza parlor, inspired a North Carolina man to go to the restaurant and fire an AR-15 rifle because he believed he could free the children. No one was injured.

In a statement, festival organizers said they canceled the event “out of an abundance of caution.”

“Not only is it disappointing that the cancellation of this event deprives the families of our school and community a day of fun and connection, but the Blue Marble Jubilee also serves as a fundraiser,” Wendy Willoughby, president of the school foundation, said in the statement. “We now find ourselves not only out the potential dollars raised at the event, but also the money already spent in preparation.”

The event was set to include an art sale, crafts, face painting, musical performances and food. Those who already bought tickets will be refunded next week, organizers said.

Mike Rothschild, who researches and debunks conspiracy theories, wrote in a blog post that it was difficult to tell whether the response to Comey’s tweet was genuine or a parody. He said Q, the supposed leader, is posting less frequently and having less of an impact.

“And so like starving villagers fanning out into the countryside to forage for whatever they can find, Q’s acolytes are latching on to interpretations and theories that stray from the realm of the possible into raw, uncut nonsense,” Rothschild wrote. “QAnon social media is full of ‘decodes’ like this. It’s a movement made for turning nothing into something, then pretending that you’ve been granted secret knowledge.”

Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@sfchronicle.com Twitter: @kveklerov