The sheriff's office said it was possible the man was pushed down the shaft at the construction site.
One worker was killed and another injured when a wall collapsed at a construction site in Pacoima.
Fifteen construction workers were rescued but one did not survive, his family said. Another worker remains unaccounted for.
Firefighters on Wednesday rescued at least three men who became stuck on cherry pickers after part of a construction site collapsed in Glendale.
Emergency workers attempted to rescue the workers from the rubble but they were both pronounced dead after being pulled from the trench.
A scaffolding collapse from 70 feet at a construction site killed 3 people in Charlotte on Monday morning.