A hoax bomb threat forced the evacuation of Congregation Beth Am in Los Altos Hills at the end of Shabbat services on Sept. 8. It was the latest in a series of similar events targeting synagogues across the United States in recent months.

The Beth Am campus was evacuated, including guest Rep. Anna Eshoo and speaker Jeremy Ben-Ami, president of J Street, whose appearance had drawn a large crowd to the Reform synagogue.

“There was no bomb or gunman on site, as a malicious 911 call had claimed,” Rafael Brinner, director of community security for the S.F.-based Jewish Community Federation and Endowment Fund, said in a Sept. 10 email. The email was sent to notify Bay Area synagogues about the potential for security threats over the High Holidays and recommend steps to mitigate risk.

Brinner said the false threat at Beth Am appeared to be another instance of “swatting.” Fremont Temple Beth Torah had a similar Friday evening evacuation in August. “We knew that it was happening,” board president Cheryl Cohen told J. at the time. “We didn’t expect it to happen to us.”

Swatting refers to 911 calls that report a fictitious crime or emergency meant to trigger the dispatch of heavily armed police. A synagogue in Arizona and a JCC in Utah also had to evacuate last weekend.

Although the threats have so far turned out to be fake, they have succeeded in disrupting services, unsettling congregants and raising security concerns as the High Holidays begin on Sept. 15 and synagogues around the country fill up with worshippers.

David Goldman, executive director of Reform Congregation Emanu-El in San Francisco, informed congregants via a Sept. 11 email that the synagogue has put enhanced security measures in place to ensure everyone’s safety at services. Some measures will be apparent to congregants, such as the presence of fire marshals, the email said. Others will be invisible.

“These measures are designed to address modern-day threats, including ‘swatting,’” Goldman wrote. “One way to refute those who wish us harm is to continue to participate in community life as we always have.”

Emanu-El is also asking congregants to be as prepared as possible, instructing them to leave large bags at home, have High Holiday confirmation emails ready to show upon arrival at services, remove any keys, phones and other metal items from pockets, and have bags open and ready for inspection.

The balance of being prepared but not afraid, that’s the balance we’re trying to keep.

“The balance of being prepared but not afraid, that’s the balance we’re trying to keep,” Goldman told J. “Our motto has always been to be proactive rather than reactive.”

Since mid-July, more than two dozen synagogues and Jewish organizations in 12 states have received the anonymous, phoned-in threats, according to the Anti-Defamation League, prompting the organization to send out its own email warnings. Black churches have also received threats.

Swatters often target facilities where services are being livestreamed, Brinner said in his email to synagogues, “so they can post video online of the disruption they caused.”

He encouraged synagogues to make their livestream links as private and secure as possible. Zoom offers a guide to keep “uninvited guests” out of livestreams, and both Google and Meta have instructions on restricting who can view a YouTube livestream or Facebook Live video.

Even with privacy restrictions in place, when an event is livestreamed, there is no sign-in and viewers are anonymous. For that reason, Congregation Beth Jacob in Redwood City will not provide livestreamed services this year for the High Holidays out of concern for safety, executive director Keren Smith said. Instead, the services can be joined through a password-protected Zoom link that will be shared with ticket-holders and registered guests.

“It was not an easy decision,” Smith said, because the Conservative synagogue had to give up the relative convenience of livestreaming in order to limit or block access to bad actors.

“If you need any help to get on Zoom, we are here to make that happen,” Smith added.

At Congregation Sherith Israel, San Francisco police officers will be stationed outside as an extra layer of security during the High Holidays, a practice the Reform synagogue has followed in previous years, according to outgoing executive director Gordon Gladstone.

Concern over the potential of a swatting incident over the holidays “is a challenge on top of many other challenges,” Gladstone said. “We wish it weren’t the case.”

In Oakland, Temple Beth Abraham’s board and clergy have discussed the threat of swatting with the police, Rabbi Mark Bloom said. However, he is doubtful that anyone targeting the Conservative synagogue would succeed in triggering the dispatch of officers to interrupt services.

“In bigger cities like ours, it might not be the priority [for law enforcement] unless they are sure that it’s real,” Bloom said. “By the time they’d show up, services would be over.”

In the wake of the evacuation at Congregation Beth Am, synagogue clergy and leaders assured congregants that High Holiday services would be held as planned, though with “increased security presence,” they wrote in the Sept. 8 email. “As a community, we remain resolute and determined in the face of this act of antisemitic harassment.”

J. interim editor Sue Barnett contributed to this report.