Authorities in San Joaquin County, CA, are warning truckers to be on the lookout for any suspicious activity following a string of truck thefts in the area.

The county, which is about midway between San Francisco and Sacramento, includes the city of Stockton. Since early April, the theft of at least 27 rigs has been reported.

KXTV, a local ABC affiliate, reported that the vehicles are often found several days later stripped of their air cleaners and chrome wheels.

The California Highway Patrol said an organized crime ring might be behind the thefts, stealing the trucks for their chrome parts, which are then resold at discount prices.

The police are urging the public to report any suspicious activities and be on the lookout for trucks that end up in unusual areas, such as orchards or open fields.