The Riverside City Police Department ramped up visible patrols around the two Jewish synagogues in the city in light of Saturday's deadly shooting at a synagogue in Poway, San Diego County.
"Our chief spoke to both rabbis to express support and concern for their facilities and congregants," Officer Ryan Railsback said.
Temple Beth El and Chabad Jewish Community Center are both located in Riverside.
According to Poway Mayor Steve Vaus, one person was killed in the shooting at Congregation Chabad and three more were injured, including the synagogue's rabbi.
The fatality was an older woman. The three injured victims were said to be in stable condition.
Authorities said they arrested the suspected shooter, a 19-year-old male, and there was no further threat.
Saturday is the final day of Passover, and it is also the six-month anniversary of a shooting at the Tree of Life synagogue in Pittsburgh, in which 11 people were killed.