CHICAGO (CBS) — A south suburban gas station gave out about $12,000 worth of free gas over a two-week period recently, but it wasn’t part of a promotion, it was because someone tampered with the pumps.

Police said the pumps were altered so that gas could be pumped out without the station attendant knowing about it. By the time someone figured out what happened, 2,900 gallons had been pumped for free and the Citgo station at 590 W. 14th St. in Chicago Heights was out of gas.

The news was shocking to drivers trying to fill up on Tuesday.

“I’m just shocked,” one man said after pulling up to get gas, and finding out the Citgo was out of fuel. “I’ve never heard anything like that before.”

The gas station’s owner was just as shocked when he discovered the gas was missing on May 5.

Kahled Mubarek, who works next door, said he believes he saw the man responsible for the theft.

“He come in everyday, about 5 or 6 times,” and use the same two pumps each time, Mubarek said. It made him suspicious, because each time the man was standing by a different car.

It appeared the man was telling motorists he could fill up their tanks for $20 in cash, which he’d pocket for himself.

“One time I hear him, he tell somebody ‘$20 to fill up the car,’” Mubarek said.

Mubarek alerted the gas station clerk, and the man left. He didn’t think much about it until he heard about the stolen gas. When he did, he immediately thought of the man he’d seen at the pumps.

“I remember the guy, and I come and look around the pump, and I see all pumps broke,” he said. A closer inspection showed not only were the locks on the gas pumps broken, but the pumps themselves had been altered to allow the man to pump gas without the clerk inside knowing.

“He broke it. He got a trick from inside, push some button, and he make the pump running,” Mubarek said.

The gas was stolen over a two-week period from April 21 to May 5. An employee said it’s possible the thief had some “inside help” from a clerk. Chicago Heights Police said they are looking into that.

As for the stolen gas, the station owner has filed an insurance claim to cover it, but for now, there’s still no gas at the pumps.

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