2007-05-31 18:55:00 PDT SAN FRANCISCO -- Dozens of drivers waited for hours on end today to take advantage of a rare sight: gas in San Francisco for less than $3 a gallon.

The going-out-of-business deal -- $2.99 a gallon for regular, a penny more for higher octane -- happened at the Shell station at Sixth and Harrison streets, which closed for good around 5 p.m. after its tanks ran dry.

The lower cost gas prompted drivers from near and far to come to the South of Market station, where they waited in lines that snaked a block down Harrison Street and lasted up to three hours for some drivers.

The Chevron station across the street was selling regular gas for $3.57 a gallon -- for once, a steeper price than its competitor across the street.

Bob Oyster, the Shell station's owner, had been in the news before. He garnered national attention earlier this month when he raised the price of gas at his station to more than $4 a gallon in what he said was a protest of Shell. He said that the company charges independent owners high prices, cutting his profits.

But on Wednesday -- one day before his station would close for good -- Oyster changed tack, lowered his prices and said he would pump gas until the last 6,000 gallons were gone. He plans to turn over the station keys to Shell on Friday.

The lines started early this morning and were still going strong around 1 p.m. when attendant Si Wong hung up an "All Out" sign in the window. Wong said the gas station still had about 4,000 gallons of regular unleaded gas left -- premium had run out an hour-and-a half earlier -- but that the computer network had gone down.

Wong was unsure when the problem would be fixed but was advising customers to move along.

Earlier, customers like Avon Curtis said it was well worth it for her to wait for 90 minutes to save $4 to fill up her Ford Focus. Many of the people waiting in line said they had heard about the deal in The Chronicle or on the morning news; some drove all the way from the East Bay and Peninsula.

"I have to think smart, I'm a single parent so I have to budget my money," said Curtis, a San Francisco resident and mother of six, who just bought a home in Oakland and said she has been driving back and forth a lot. "I fill up every five days."