The shooter who was identified today as 48-year-old Andre Turner of Norco, a Southern California Edison employee, the City News Service reported.
The two people killed were also identified as 56-year-old Henry Serrano of Walnut and 53-year-old Robert Lindsay of Chino, according to Lt. Larry Dietz of the Los Angeles County Department of Coroner.
Police from several towns converged on the Irwindale office building Friday afternoon after receiving reports of a gunman in the facility.
As police swarmed in, employees of the building filed out of the structure with their hands raised in the air.
Turner, believed to have shot himself, died at the scene. One victim also perished there and another passed away while taken to the hospital, said Capt. Mike Taylor.
The remaining two victims—a woman and a man—were listed in critical condition at a local hospital, according to the Los Angeles County Sheriff's Department.
CBS2 reported that Turner walked into the Irwindale office building that houses more than 1,100 SCE employees and methodically began shooting other employees.
The building's employees primarily work in the company's Information Technology and Transmission and Distribution divisions, according to an Edison official. The station also reported that Lindsay was an operations manager in the IT division at SCE and was a father and husband.
The sheriff's department has not yet released a motive for the attack. Sheriff's officials said a semi-automatic handgun was used for the shooting.
The shootings occurred about 1:30 p.m. in the 4900 block of Rivergrade Road at Rivergrade Building 3 of the SCE facility. Company officials later confirmed the shooter was a Southern California Edison employee and that those who were shot were also associated with the company. Three of the victims were employees and one was a company contractor.
The Los Angeles Times reported the shooter told some people to leave before the shootings began. He methodically picked off co-workers, including some Edison supervisors, the newspaper reported.
According to KCAL9, a budget meeting was held and cuts were discussed before the shooting began, but police would not say if the threat of layoffs set off
KCAL9 also reported the shooter was underwater financially on his house, and police later searched his Norco house.
Sheriff's officials said the shooter and all the victims, three men and one woman, worked in the same general area of the building.
Employees who were in a break room when the gunfire broke out barricaded themselves in the room by pushing a refrigerator in front of the door, a man who said his girlfriend works in the building told KCAL.
Gil Alexander of Edison told reporters at the scene that the company does not occupy the entire building, but the Edison portion of the office building is accessible only by using a security card.
Ted Craver, chairman and chief executive officer of Southern California Edison's parent company, Edison International, called the shootings "one of the most horrible days in our company's history."
"We are deeply saddened by [Friday's] tragic events," Craver said. "We are providing counseling to employees affected by this event."
in nearby Baldwin Park was locked down immediately after the shooting, as was .