A longshoreman has died after a vehicle he was driving at the Port of Los Angeles plunged into murky waters, a port spokesman said Monday evening.

The man was operating a utility tractor rig on a dock at the Evergreen terminal when it fell into the main channel off Terminal Island on Monday afternoon.

The vehicle, similar to a big-rig cab and chassis, is used to move shipping containers. 

The vehicle sank to the bottom of the 50-foot channel, where the victim was pulled from its cab by Los Angeles Fire Department SCUBA divers, officials said.

It was unclear how the vehicle ended up in the water, where rescue divers encountered zero visibility during their search for the man.

"We're not sure what happened. That's what's being investigated," port spokesman Phillip Sanfield told The Times.

The man was taken on an LAFD boat to a nearby fire station as rescuers tried to revive him. His name and age were not released.

Sanfield said longshoreman have a "high-risk job" but added that Monday's incident was an "unusual occurrence."

ALSO:

LAPD seeks clues in Mid-Wilshire shooting death

Firefighter killed in Arizona died 'doing what he truly enjoyed'

Riverside County man held on suspicion of setting 9 wildfires

Twitter: @LAJourno

robert.lopez@latimes.com