It's like a scene out of a horror movie: A fiery mystery hidden in the fog.

Cars are being set on fire in the dark of night, spotted by drivers between Lodi and Lockeford.

"Sometimes they get burned up so much so you can't tell where they came from or what they are," Mokelumne Rural Fire District Chief Mark Weber said.

Chief Weber has been with the Mokelumne Rural Fire District for 25 years. While car fires are common for his department, he says the amount in the past two months is not.

"Just the past couple months, we had an uptick in vehicle fires within our fire district," Weber said. "We noticed that quite a few have been happening. We had about seven so far that are suspicious in activity."

Two in October, three in November, and already two in December.

Some have been stolen, and all are abandoned in the thick tule fog in complete darkness.

"Obviously, if it's dark and it's in the middle of the rural areas at night, not too many people around, it's where they're getting dropped off at," Weber explained.

He says while no one has been hurt, the risks remain for his crew and others.

"It's a danger to the firefighters, danger to the health of the public and area -- and if it's not secluded, it's near a building or something like that, it can catch a building on fire," Weber shared.

Now, they're trying to find who is responsible and asking the community to step in.

"We're just keeping an eye on it," he said. "We want the public to know that if you see any suspicious activities, report it. Call 911 or law enforcement and let us know what's going on. We're just happy this is happening not during the summertime because they are still dangerous, but we don't want this to continue."

The chief says the last time he saw something similar to this uptick was in the early 2000s.

CBS Sacramento is waiting to get additional details on the vehicles from the San Joaquin County Sheriff's Office.