A man was detained for questioning after reports of a shooting at a synagogue in the California city of Poway, according to the San Diego County Sheriff's Department's Twitter account on Saturday.
The synagogue is Congregation Chabad, CNN affiliate KGTV reported.
The Palomar Medical Center Poway received four patients from the shooting, according to a hospital spokeswoman. Their conditions are unknown.
Poway Mayor Steve Vaus said the congregation was targeted by "someone with hate in their heart ... towards our Jewish community and that just will not stand."
He told CNN, "I also understand from folks on the scene that this shooter was engaged by people in the congregation and those brave people certainly prevented this from being a much worse tragedy."
KGTV reported that a witness heard six or seven shots followed by screams and then another volley of shots. The witness said the rabbi tried to calm the gunman and members of the congregation even after the rabbi was wounded, the station reported.
The San Diego Police Department is assisting sheriff's deputies with the incident, according to a tweet from Chief David Nisleit.
"No known threats however in an abundance of caution, we will be providing extra patrol at places of worship," Nisleit said.
Deputies were called to the synagogue about 11:30 a.m. (2:30 p.m. ET). The synagogue's Facebook page said a Passover celebration was scheduled for 11 a.m.
Passover, one of the holiest Jewish celebrations of the year, ends Saturday.
The incident comes months six months to the day after the shooting at the Tree of Life synagogue in Pittsburgh.
On October 27, Robert Bowers stormed the synagogue, killing 11 people in what the Anti-Defamation League said was the deadliest anti-Semitic attack in US history.A federal law enforcement official said at the time that Bowers made anti-Semitic statements during the shooting and targeted Jews on social media.
The Chabad of Poway website said the congregation is a center for Jewish people of all backgrounds. It was established in 1986.
Poway, about 20 miles north of San Diego, has about 48,000 residents. It is an upper-middle-class community that calls itself "The City in the Country." The city website said it has one of the lowest crime rates in the state.