WOODSTOCK – In 1929, a gallon of gas was $0.21.

At a gas station in Woodstock on Sunday night it was about 20 cents cheaper.

An error at the Shell station at 315 N. Madison St. had gas priced at $0.011 per gallon, causing a flurry of traffic and police activity at the store.

Star 105.5 posted a picture of a listener's gas receipt to its Twitter and Facebook pages that showed a 10-gallon purchase totaling only $0.12.

The receipt was confirmed by Shell employee Drita Castillo, who said nothing like that has ever happened in the five years she has worked at the station.

"The first thing I did was run outside this morning to make sure the pumps were OK," said Castillo, who wasn't working last night and was informed of the malfunction by customers Monday morning. "It's not good for business."

Woodstock Police arrived to the gas station between 9:30 and 10 p.m. to find cars lined down the street and blocking traffic, according to Woodstock Police Srgt. Dennis Leard. After initially clearing the congestion, the cars immediately began forming lines again at the gas station, Leard said.

At that point police further investigated the issue and discovered the drastically low gas prices.

"The clerk didn't appear to be aware [of the price change]," Leard said. "We made him aware of the situation and instructed him to shut off his pumps and fix the problem."

The police ultimately hit the emergency shut off button and the gas station was closed for a period of time before opening back up with its regular prices.

The error kept the discounted gas available for approximately two hours, Leard said.

Patrick DeHaan, a senior petroleum analyst at Gas Buddy, said a malfunction like the one in Woodstock is "extremely rare."

"I don't know that I've ever seen gas for a cent," he said.

The mistake could have been a computer error or a human error, as price changes need to be keyed in by an employee, DeHaan said.

A photo posted to Star 105.5's Facebook page by listener Emmanuel Flores shows a line of cars waiting to buy gas.

Brad Blalock told the Northwest Herald his friend texted him about the low price, but when he arrived "the cops were shutting it down."