The Beverly Hills synagogue says it was established in shared space in 1980 to serve Iranian Jews, many of whom fled religious persecution following Iran's Islamic Revolution in 1979.
The city of Beverly Hills calls Nessah "the largest Persian-Jewish congregation in the United States." About one in five of the city's 34,000 residents are thought to have Iranian heritage. Together with neighborhoods on Los Angeles' Westside, the local Iranian diaspora is sometimes called "Tehrangeles."
"This cowardly attack hits at the heart of who we are as a community," Mayor John Mirisch said in a statement. "It is not just an attack on the Jewish Community of Beverly Hills; it’s an attack on all of us. The entire City stands in solidarity behind Nessah, its members and congregants."
Eric Garcetti, mayor of nearby Los Angeles, tweeted that he was "shocked and outraged."
"We will stand together and speak out strongly against any act of hate and intolerance in our community," he said. "We're keeping our friends and neighbors in our thoughts as police investigate."
Police said the synagogue will undergo cleanup and reopen Sunday.
Dennis Romero writes for NBC News and is based in Los Angeles.