Employees from the Southern California Edison facility in Irwindale were back at work Tuesday for the first time since a shooter before taking his own life.
Detectives from Los Angeles County Sheriff's Department said they have not yet determined a motive, but they learned Andre Turner, the alleged shooter, had been reprimanded for missing an audit deadline before the shooting.
It was not clear when the reprimand was delivered to him.
The two people Turner killed were according to Lt. Larry Dietz of the Los Angeles County Department of Coroner.
Police authorities have also released parts of the initial 911 call about the shooting (see video attached to hear the tape).
On the 911 recording, a caller tells the operator that gunshots are being fired.
"There are gunshots occurring outside the facility in the parking lot," the caller says.
"Who is firing?" the operator asked.
"We don't know," the caller says.
, and flags were at half staff at all Edison buildings to remember the victims of the senseless tragedy.