Federal immigration agent Ezequiel Garcia, 45, had also told his wife he was having trouble at work before he allegedly shot Deputy Special Agent in Charge Kevin Kozak Thursday, the Los Angeles Times reported Saturday.
Federal officials said Friday Garcia shot Kozak in his upper torso, legs and hands before being fatally shot by a third agent in the Long Beach federal building.
Kozak is in stable condition and is alert and speaking, the officials added.
"This guy's a fighter," said a witness, whose name was not reported. "He was awake and lucid."
The third Immigration and Customs Enforcement agent, whose name was not reported, was put on leave out of "concern for his privacy," officials said at a news conference Friday.
"Kozak is alive today because of the heroic action of another ICE supervisor," Special Agent in Charge Claude Arnold said. "This is the first time anything of this nature has occurred within ICE. And we're doing everything humanly possible to make sure it doesn't happen again."