A 68-year-old man suspected of killing one and injuring five others during a shooting at a Laguna Woods church Sunday had secured the doors with chains and placed explosives at the scene beforehand, officials said.

David Chou was allegedly “upset with political tensions between China and Taiwan,” when he opened fire during a lunch banquet after morning service at Geneva Presbyterian Church on the 24000 block of El Toro Road, according to Orange County Sheriff Don Barnes.

Chou had driven to the church which he had no obvious ties to, locked the church doors with chains and tried to disable the locks with glue, Barnes said during a news conference Monday afternoon.

Around 50 people were gathered to celebrate the return of a pastor who was on a mission trip in Taiwan.

Chou was not known to the congregants, but he joined the gathering and was walking around before he started shooting. Orange County District Attorney Todd Spitzer said he “socialized and mingled,” beforehand.

A churchgoer, 52-year-old John Cheng, tackled Chou and tried to disarm him, allowing others to subdue the suspect and ultimately tie him up until police arrived.

Cheng, however, was shot in the process and died. His actions were described by authorities on Monday as heroic.

Cheng, a doctor who worked in sports medicine, was at the banquet with his mother.

Five other people were injured, including a married couple in their 80s, Barnes said.

Two 9 millimeter semi-automatic pistols were at the scene, along with several bags that contained magazines with additional ammo and four Molotov cocktail-like incendiary devices that Chou had allegedly placed around the church, Barnes said.

In Chou’s car, authorities found notes in Mandarin that showed “hatred of the Taiwanese people.”

The FBI said they opened a federal hate crimes investigation into the incident.

Barnes described the shooting as a “heinous crime.”

Chou is facing one count of murder with the use of a gun, five counts of attempted murder and four counts of unlawful possession of explosives, Spitzer said.

The suspect, a Chinese immigrant who works as a security guard in the Las Vegas area, also faces a special circumstances allegation of lying in wait.

He could face the death penalty or life in prison.

Spitzer he wanted to see the crime scene for himself to determine how to proceed with the case.

“I needed to see with my own eyes the havoc, the despair, the urgency, the emotion and the lives that he has forever affected and ruined,” the top prosecutor said.