SCE says more than 250 people turned out for a memorial service to remember those lost in the tragedy, including family of the victims.
"We're like a family. We're all grieving," said Lois Pitter Bruce, an SCE employee. "There is no happiness for us. No matter how much you explain it, you can't understand it."
Authorities continued to investigate what drove Andre Turner, 48, to shoot and kill 53-year-old Robert Lindsay and 57-year-old Henry Serrano, before turning the gun on himself.
Turner also shot and injured Angela Alvarez, 46, an Edison employee, and Abhay Pimpale, 38, an independent contractor.
Pimpale was released from the hospital Saturday afternoon, but Alvarez was still in critical condition.
SCE has set up a fund to help the victims and their families. The company is also providing grief counseling for its employees.
The Irwindale office will be closed Monday.