MARTINEZ (CBS SF) — Authorities are investigating a rash of boat thefts in the Sacramento-San Joaquin River Delta in recent months, sheriff’s officials said Friday.

Contra Costa County Sheriff’s Office spokesman Jimmy Lee said more than a dozen boats have been stolen in the county in the past few months.

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Authorities have made some arrests but sheriff’s officials didn’t release any information about who was arrested and what charges the suspects are facing.

Some suspects are still at large, according to Lee’s news release.

They are targeting boats for outboard engines and tower speakers.

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According to sheriff’s officials, the boats many times are stolen, stripped and then either abandoned, grounded or dumped. Sometimes thieves set them on fire.

Sheriff’s deputies are asking boat owners to use a chain to secure their vessels to a dock, use motion lights and cameras and remove valuables from their boats.

Anyone who witnesses suspicious behavior is asked to call 911. The sheriff’s office marine services unit can be reached at (925) 427-8507.

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