Authorities said witnesses described 48-year-old Andre Turner as methodical and calm as he walked into the Irwindale office and gunned down his coworkers on Friday.
Turner was a systems analyst who has been with SoCal Edison for 7 years. He shot four people before taking his own life.
Walnut resident Henry Serrano, 56, was shot in his office, as was 53-year-old Robert Lindsay of Chino. Both were supervisors for Edison.
Turner also shot and injured Angela Alvarez, 46, an Edison employee, and Abhay Pimpale, 38, an independent contractor. Pimpale was released from the hospital over the weekend, while Alvarez remains in serious condition.
Flags have been at half staff at all Edison buildings to remember the victims of the senseless tragedy.
SoCal Edison set up a $100,000 fund for the victims' families and will also have grief counselors available to employees.
"Our focus right now and continues to be on the families and the victims, trying to help them every step of the way during this very, very difficult time," said Steve Conroy of SoCal Edison. "Our executives have met with family members and they have been very appreciative of that. Those have been difficult, as you can imagine, meetings. But we are doing what we think is necessary to help them during this very difficult time."
Investigators are still trying to determine a motive to the shooting spree. They said that Turner had been given a verbal reprimand for missing an audit deadline.
They also say that there was an indication that he may have had financial troubles. A real estate agent who knew Turner said that he was possibly short-selling his $1 million home in Norco for less than half of its worth.
On Monday a 911 tape was released describing the scene of terror at the SoCal Edison office. A security guard mistakenly told the operator that the gunfire was coming from the parking lot.
"There are gunshots occurring outside the facility in the parking lot," the caller says.
"Who is firing?" the operator asked.
"We don't know," he says.
More than 250 people turned out for a memorial service on Sunday to remember those lost in the tragedy, including family of the victims.