A maintenance worker at Temple Beth Torah, a Reform synagogue in Fremont, discovered a swastika etched on the outside of the building on Wednesday.

The swastika appeared to have been drawn in black marker or thick pen onto a stucco wall. It measured about 5 square inches, the synagogue reported in an email to congregants.

It was not known when the vandalism occurred, as the synagogue had been closed due to the pandemic and the maintenance worker who found it comes only every other month.

Temple administrator Jill Ziman and president Ronnie Petersohn met with Fremont police at the shul. Officers asked neighbors for video footage from their security cameras, the synagogue reported.

“It’s disturbing,” Ziman said. “It’s sad that this still happens.”

Police said they would be treating the incident as a hate crime, Petersohn told congregants in the email.

A Fremont Police Department spokesperson did not respond to a request for comment in time for this article.

Roughly two decades ago, before Ziman joined the synagogue staff, she said the shul experienced a similar instance of antisemitic graffiti, though a “much larger area” was defaced, she said. Since then the synagogue has not reported any antisemitic incidents.

According to its H.E.A.T. Map visual database, the Anti-Defamation League has recorded five hate incidents in Fremont since 2018. Three were instances of white supremacist propaganda distributed by the group Patriot Front, a right-wing extremist group; the most recent occurrence was on Dec. 22.

Fremont is a city of 235,000 in Alameda County. Temple Beth Torah is a congregation of about 140 families. It also hosts a preschool, Gan Sameach.