ST. JOHNS COUNTY, Fla. -

The St. Johns County Sheriff's Office issued a warning to residents in the northeast part of their county, saying they've seen an increase in vehicle thefts and warning residents to keep their car doors locked.

The Sheriff's Office said it is a preventable crime, but since Jan. 1, deputies have seen an increase in car thefts, and the main reason why crooks were able to break in is because those cars were left unlocked.

"Please lock your vehicles, set your alarms. Don't leave valuables in your vehicle overnight," said Sgt. Catherine Payne, of the St. Johns County Sheriff's Office. "It's very important to keep your vehicle in a well-lit area and if you have a garage, park it in your garage."

In the first 13 days of the new year, there have been 35 auto burglaries reported to the Sheriff's Office, and 86 percent of those vehicles were left unlocked.

"There's nothing significant about the vehicle make and model. Most of these vehicle burglaries are parked at residences and it happened overnight," said Payne.

Payne told Channel 4 that thousands of dollars' worth of personal items were stolen, including guns. Payne said it's unclear if the crime is being done by the same person or group of thieves, but said until those who are responsible are caught, it's best to keep items in cars out of sight and out of the minds of criminals.

"Our detectives are working diligently," said Payne. "They feel like they have a pretty good handle on the cases and that there are some links, so we are going to see in the next few weeks probably some solved cases come out of this."