Another person has minor injuries, said the tweet.
The shooting happened at the Geneva Presbyterian Church during a lunch reception to honor a former pastor of a Taiwanese congregation that uses the church for its worship services, according to Tom Cramer, a presbytery leader.
Police have a suspect in custody, Orange County Undersheriff Jeff Hallock said during a news conference on Sunday evening. He is believed to be an Asian man in his 60s who doesn’t live in the area, said Hallock.
Investigators are working to determine whether he has any connections to the church or its congregants, a statement from the sheriff’s department said.
Police do not yet have a motive, said Hallock.
The suspect was detained at the scene after a group of people at the church were able to hogtie his legs with an extension cord and confiscate at least two handguns from him, said Hallock.
“That group of churchgoers displayed what we believe is exceptional heroism in interfering or intervening to stop the suspect,” he said.
Authorities said the victims injured in the shooting included four Asian men, ages 66, 75, 82 and 92, and one Asian woman age 86.
“The identity of the decedent will be released pending official identification by the Coroner and notification of next of kin,” a statement from the sheriff’s office said.
About 30-40 people were in attendance at the reception, said Hallock.
California Gov. Gavin Newsom said his office is “working closely with local law enforcement.”
The Taiwanese congregation, which became a sister congregation at Geneva Presbyterian Church about five or six years ago, always holds a lunch after their Sunday morning service, Laguna Woods Mayor Pro Tem Cynthia Conners told CNN.
“We’ll see what we can do to meet with the members of the congregation, we’ll bring in someone from the Orange County Human Rights Commission … and try to make sure that the Asian members of our community feel as safe as all the other members of our community, although I would have to say I think we all feel a little less safe today,” Conners said.
Taiwan’s government says its Economic and Cultural Office in Los Angeles has activated emergency response plans.
“The Ministry of Foreign Affairs sends our deepest condolences to the victims and their families,” Ministry of Foreign Affairs spokesperson Joanne Ou said. “We will keep in touch with the family members of the victims to understand their needs, and provide all necessary help,” she added.
CNN’s Jenn Selva, Amanda Jackson, Dawn Tamir and Jordan Guzzardo contributed to this report.