FRANKLIN COUNTY, WA -- From the outside, an old brown van looked inconspicuous. But on the inside, an intricate system was laid out, jimmy-rigged to steal hundreds of gallons of gas.

"This can hold 300 to 400 gallons of gas," Franklin County Sheriff's Detective Lee Barrow said.

The system started with an electric pump that funneled the gas through a long tube, into a nozzle and into the massive red tank. It was all wired to the car battery, where alligator clips held it tight underneath the engine. The only outward sign of thievery was a hose that ran outside near the back tire.

"In 20 years, I haven't seem this particular type of contraption," Barrow said.

At roughly $2.80 a gallon for regular unleaded and $3.00 a gallon for diesel, it's probably no surprise that criminals are getting more creative. Detective Barrow said the two suspects, from the Yakima Valley, likely hit up dozens of gas stations on the way to the Tri Cities.

"They can sell thousands of gallons of gas a day, and steal thousands of dollars with just this one van," he said.

And they're not just stealing it. Barrow said they're selling it at cut rate.

"They'll go out and hawk the diesel. They'll drive it around and look for some excuse," he said.

The gas-thieving plot all unraveled when the suspects tried stealing diesel at the Wondrack gas station on E. Vineyard Drive, a few miles north of Pasco. Although the station is in a rural area and usually unmanned, an employee happened to see a brown van parked near the pumps for hours. The van was shielded by a black pick-up who's owner seemed to be having car trouble. Later, that same employee saw the brown van abandoned on the road. When he took a peak inside, he noticed the tank and called the Sheriffs Office.

That's when detectives realized "car trouble" was just a thinly-veiled distraction to hide the suspected theft. When Barrow searched the van, he only found a bit of diesel inside the tank.

Even if the men didn't manage to make off with much gas, a search warrant led them to find a critical piece -- the cap covering for the underground pumps -- that links them back to the gas station and an attempted theft.

"This is an obvious piece of evidence we needed," Barrow said pointing to the cap.

"It does surprise me. You didn’t say what time it happened but I could see that happening at night," Joel Westbrook said, a truck driver who regularly gasses up at the Wondrack on Vineyard.

At this point, deputies aren't sure how extensive the operation is. There could be just one van or a dozen. But as much gas as they expect was stolen, the suspects could face felony charges for attempted theft.