By Ian Schwartz

STOCKTON (CBS13) – An unusual theft ring is targeting freight yards, but they aren’t stealing the cargo — just the containers.

The containers are worth more than $100,000 when filled, but the people stealing them are doing so when they’re empty, but they’re still making a lot of money.

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Ernie Castro with Logistics Terminals, near Stockton, says the empty containers semi-trucks pull cost $25,000.

“This year we’ve had six units taken from us. It started in January and ended in March,” he said.

The thefts are part of a ring California Highway Patrol says stretches from the valley to the East Bay.

Crooks drive onto the property of cargo storage places, attach a container to a truck and drive away. Then, they strip off the decals and re-paint the containers.

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“They resell them to farmers. Farmers buy them and put their tractors in them, their equipment inside of them,” said Castro.

CHP detained several people and recovered hundreds of thousand of dollars worth of equipment in a raid near Lodi last week.

Castro says police found one of his containers recently on a farm, but the chassis it sits on was never recovered.

“The chassis, they are not reusable. They can’t sell them, so they end up cutting them up and scrapping them,” he said.

Castro says they’ve added more cameras, more security and informed staff to keep an eye out to prevent more theft of the very expensive containers.

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CHP hasn’t released the names of anyone they detained because their investigation is ongoing.