Burbank, CA (AP)  -- Police are investigating a whopper of a fuel theft from a service station in Burbank.

Police on Monday said the service station's owner reported 4,000 gallons of diesel disappeared sometime before 5 a.m. on Friday.

Burbank police Detective Sam Anderson says when the gas station opened at that time, workers found the underground diesel tanks had been drained.

The tanks were not locked, Anderson says, but a special device is needed to open them.

Anderson says there is no video footage of what happened, but whoever stole the fuel must have been driving a tanker truck.