The fire was reported around 12:10 p.m. in the 12100 block of West Olympic Boulevard, according to the Los Angeles Fire Department.
Fire officials say rebar became electrically energized and apparently made contact with high voltage lines, sparking the blaze.
Two workers were able to evacuate the building, but a third did not survive.
Firefighters were able to knock down the fire in about half an hour.
LADWP and Southern California Edison were called in to ensure the building was de-energized, officials said.
The two injured workers were transported to a local hospital in unknown condition. Additional information, including their ages, was not immediately released.