'Anti-Taiwanese hate sparked US shooting'

Orange County Sheriff Don Barnes said the motive of the shooting was a grievance between the shooter, identified as a Chinese immigrant, and the Taiwanese community. 

Barnes said the suspect drove to the Orange County church, where he was not a regular attendee, secured the doors and started shooting. 

The gunman had placed four Molotov cocktail-like devices inside the church, the sheriff said.

Barnes said Cheng, survived by a wife and two children, heroically charged at the shooter and attempted to disarm him, allowing others to intervene. 

A pastor hit the gunman on the head with a chair and parishioners hog-tied him with electrical cords. 

But Barnes said Cheng was hit by gunshots.

"Understanding that there was elderly everywhere and they couldn't get out of the premises because the doors had been chained... he took it upon himself to charge across the room and to do everything he could to disable the assailant," said Orange County District Attorney Todd Spitzer.

Congregant Jerry Chen, 72, a longtime member of the Irvine Taiwanese Presbyterian Church, which worships at Geneva Presbyterian Church in Laguna Woods said he saw church members screaming, running and ducking under tables. 

The Orange County Sheriff's Department tweeted that David Chou, 68, of Las Vegas has been booked on one count of murder and five counts of attempted murder.

The suspect lawfully purchased the two 9mm pistols in Las Vegas, said Stephen Galloway, ATF Los Angeles assistant special agent in charge.

There is a lot of evidence that the suspect "had an absolute bias against the Taiwanese people, its country, as a Chinese or mainland national," Spitzer said.

The suspect left notes in his vehicle concerning "his hatred of the Taiwanese people," the sheriff said.

Jail records show Chou is being held on $US1 million ($A1.4 million) bail. 

It is not immediately known whether he has a lawyer who can speak on his behalf.