A man opened fire at a southern California church on Sunday, killing one person and injuring several others before being stopped and tied up by parishioners in what an official called an act of “exceptional heroism and bravery”.

Four people were critically wounded by gunfire at Geneva Presbyterian Church in the city of Laguna Woods, 50 miles south east of Los Angeles, Orange County Sheriff’s Department officials said. A sixth person had minor injuries but was not struck by bullets.

The suspect in the shooting, an Asian man in his 60s, was in custody and deputies recovered two handguns at the scene, undersheriff Jeff Hallock said.

Orange County Sheriff’s deputies check the identification of a person trying to gain access to a parking lot by Geneva Presbyterian Church in Laguna Woods
The suspect, not shown, in the incident is being held by police (Damian Dovarganes/AP)

A motive for the shooting was not immediately known but investigators did not believe the gunman lives in the community, he said.

The majority of those inside the church at the time were believed to be of Taiwanese descent, said Carrie Braun, a sheriff’s spokesperson.

Between 30 and 40 members of the Irvine Taiwanese Presbyterian Church were gathered for lunch after a morning church service at Geneva when gunfire erupted shortly before 1.30pm (9.30pm), officials said. When deputies arrived, parishioners had the gunman tied-up and in custody.

Crime scene tape is stretched across an area at Geneva Presbyterian Church in Laguna Woods
All of the victims of the attack were Asian Americans, authorities said (Damian Dovarganes/AP)

“That group of churchgoers displayed what we believe is exceptional heroism and bravery in intervening to stop the suspect. They undoubtedly prevented additional injuries and fatalities,” Mr Hallock said.

“I think it’s safe to say that had people not intervened, it could have been much worse.”

All the victims were Asian American adults and the youngest of the victims is 66-years-old, Ms Braun said.

The investigation was in its early stages, Mr Hallock said. He said the many unanswered questions include whether the assailant attended the church service, if he was known to church members and how many shots were fired.