"Out of Gas" signs and yellow caution tape were draped across pumps that were out of gas in parts of the United States early Thursday after many retailers were overrun by panicked motorists looking to top off their tanks as prices soared past $3 per gallon and reports of shortages spread.

Many gas stations in and around downtown Atlanta had run out of gas by sunrise. The same was reported in elsewhere, including parts of North Carolina, West Virginia, Wisconsin and Arizona.

"People have kind of panicked and they're waiting in long lines because they're afraid the prices are going to go up," said Jan Vineyard, executive director of the West Virginia Oil Marketers And Grocers Association. "We're going to have some outages."

Price hikes were evident at stations nationwide Wednesday, the result of fuel pipeline shutdowns and delayed deliveries since Hurricane Katrina (search) devastated Louisiana and Mississippi earlier this week.

Gas prices jumped by more than 50 cents a gallon Wednesday in Ohio, 40 cents in Georgia and 30 cents in Maine. The increases followed price spikes on wholesale and futures markets Tuesday after the hurricane knocked off-line refineries and pipeline links along the Gulf Coast (search) that provide about a third of the country's gasoline supplies.

Concerns are now mounting over limited supplies of gasoline, including the possible return of long lines and scarcity reminiscent of the 1970s gas crisis.

"It's crazy," said Mike Currie, shaking his head as he topped off his truck's tank with gas at a station in his hometown of Bismarck, N.D. "I'm going to have to consider buying a Moped."

Continuing fears about tight supplies caused by Katrina caused gasoline futures to jump more than 10 cents a gallon Thursday.

Analysts expected some relief once electricity is restored to Gulf Coast pipelines and refineries, but they are unsure how long that will take.

This week's increases come atop a 40 percent price rise in the last year that boosted the average retail price of unleaded regular to $2.61 a gallon nationwide last week, Energy Department figures show.

"We don't have a shortage of gasoline. We have a delivery problem," said Bill Weatherspoon, executive director of the North Carolina Petroleum Council, which represents major retailers that get gasoline from the pipelines.

Although police in Charlotte, N.C., reported prior to daybreak that only 30 of Mecklenburg County's 230 fueling stations were out of gas, that number appeared to grow considerably Thursday as drivers continued to crowd the open stations, fearing a shortage. On some busy streets, stations that did have gas were seeing lines that were causing traffic backups.

Charles Richardson, assistant manager of a gas station in Charlotte, said his station was one of the few in the city that had received gas since Monday. "We ran out yesterday, but we got a drop this morning," he said.

Vineyard said independent stations without supply contracts may be affected, as well as stations who cannot afford the fuel to sell.

"We just ask people not to panic and please conserve," said Vineyard, whose organization represents almost all of the approximately 1,300 service stations in West Virginia. "Supplies are going to be very tight."

In Georgia, a few gas stations were charging as much as $6 per gallon Wednesday after other retailers had run out of gas and long lines were reported across the state. In response, Gov. Sonny Perdue signed an executive order authorizing state sanctions against gas retailers who gouge consumers.

"I'm frankly embarrassed for our state and some of our businesses that we have to do this," said Perdue, after pleading with Georgians to remain calm.

In New Jersey, acting Gov. Richard J. Codey ordered increased state inspections at gas stations for possible price gouging.

The market did receive some help Wednesday when the federal government said it would loan oil from the Strategic Petroleum Reserve (search) to refiners facing shortfalls. And the Environmental Protection Agencysaid it would temporarily allow gasoline retailers nationwide to sell fuel that does not meet stringent summer air-quality standards.

"The EPA waiver was a big move," said John Kilduff, an analyst at Fimat USA in New York.

Several gas stations in the Milwaukee area ran out of gas for several hours at the time, having to post "Out of Gas" signs at their pumps. The outages were blamed more on logistical problems on the supply end than any increase in demand.

"Everybody is really trying hard. But it has been very, very difficult to get enough gasoline," said Jim Fiene, senior vice president of the Open Pantry convenience store-gasoline station chain in southeast Wisconsin.

The problems soon could extend far beyond motorists' wallets. Energy experts say they are concerned about how hurricane damage to Gulf Coast natural gas and heating oil facilities will affect heating bills this winter. Rising jet fuel costs because of the hurricane also have put additional pressure on cash-strapped airlines.

In Georgia and North Carolina, state officials asked residents to conserve gas and government workers were ordered to limit nonessential travel. A suburban Atlanta vanpooling program also reported a 50 percent jump in participants since Hurricane Katrina slammed into the Gulf Coast on Monday.

Atlanta's commuter rail system also saw increased traffic Thursday.

"I can tell you there are definitely a lot more people riding today. This lot is never nearly this full this early," said long-time rail commuter Tony Williams, referring to a packed parking lot at a train station east of Atlanta.

The latest nonpartisan Field Poll found that California residents are changing their behavior as a result of high gas prices. Forty percent — and 54 percent of those making less than $40,000 — said they have cut back spending in other areas. About two-thirds of residents say they shop around for filling stations offering cheaper gas, and 59 percent said they are driving less.

Herbie Howard, who owns four stations in Toledo, Ohio, and supplies gas to 17 others, spent hours on the phone hunting a decent price from his suppliers. He had to pay $3.18 a gallon — 9 cents more than he was selling it for.

"We aren't making any money," he said. "We're just minimizing our loses, but no one believes you. They think we're price gouging."

Matt McKenzie, spokesman for from AAA-Northern New England, predicted gas prices would hit $3.70 to $3.80 by month's end in that region of the country, causing frugal motorists to begin carpooling, curbing errands and maybe even scaling back fall leaf-viewing trips.

In Charlotte, N.C., many gas stations were shut down Wednesday night, with yellow caution tape blocking dormant pumps.

At one of the few stations open, Steve Clifford, 48, pumped fuel into his Isuzu sport utility vehicle.

"I heard it was going to go up to $4 a gallon tomorrow and there were going to be shortages, so when I got home from work I kissed my wife goodbye and said I was going out to find gas," he said.