Updated

The alleged gunman who killed four people, including a 9-year-old boy, inside a Southern California business complex this week and opened fire on responding police officers have been charged with multiple murder counts, authorities said Friday. 

Aminadab Gaxiola Gonzalez, 44, remains hospitalized in stable condition after being shot by officers. He faces four counts of murder, one count of attempted murder and two counts of attempted murder of a police officer.

He also faces multiple gun enhancement charges.

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Authorities said Gonzalez entered a business complex on Lincoln Avenue in Orange, about 30 miles south of Los Angeles in Orange County, on Wednesday and opened fire. 

Aminadab Gaxiola Gonzalez, a 44-year-old Fullerton, Calif., man is the suspect in a shooting that occurred inside a counseling business in Orange, Calif., on Wednesday. A child was among four people killed Wednesday in the shooting at a Southern California office building that left a fifth victim wounded and the gunman critically injured, police said. (Orange Police Department via AP)

Aminadab Gaxiola Gonzalez, a 44-year-old Fullerton, Calif., man is the suspect in a shooting that occurred inside a counseling business in Orange, Calif., on Wednesday. A child was among four people killed Wednesday in the shooting at a Southern California office building that left a fifth victim wounded and the gunman critically injured, police said. (Orange Police Department via AP)

"The taking of the life of another human being is the most serious of crimes and the slaughter of multiple people while they were essentially locked in a shooting gallery is nothing short of terrifying," Orange County District Attorney Todd Spitzer said in a statement.

When officers arrived at the scene, they found the gate to the complex had been locked with a lock similar to a bicycle cable. Gonzalez fired upon two officers, who returned fire from outside and wounded him, authorities said. 

Once inside the complex, officers found the four dead victims. 

Authorities identified them as  Luis Tovar, 50; Leticia Solis Guzman, 58; Jenevieve Raygoza, 28; and Matthew Farias, 9. Gonzalez and the victims had personal and business relationships with each other, authorities said. 

A woman was wounded and taken to a hospital where she remains in stable condition. 

KABC, the ABC-owned TV station in Los Angeles reported that police that the shooting was not "a random act of violence" and that Gonzalez knew all the victims. The target was Unified Homes, a mobile home brokerage business.

Orange County District Attorney Todd Spitzer talks during a Thursday news conference at the Orange Police Department headquarters in Orange, Calif. (AP Photo/Stefanie Dazio)

Orange County District Attorney Todd Spitzer talks during a Thursday news conference at the Orange Police Department headquarters in Orange, Calif. (AP Photo/Stefanie Dazio)

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"He normally doesn't go there," Zef Farias, the boy's uncle, told The Associated Press. "They were just part of the collateral damage."

Wednesday's shooting came amid two other mass shootings in Colorado where 10 people were killed and the Atlanta area where eight people died.