COLUMBIA, S.C. — Gas stations throughout North and South Carolina continue to register some supply shortages, but gas prices in both states are slowly coming down, a spokeswoman for AAA Carolinas said Monday.

"Retailers are getting much smaller deliveries than they expected," Carol Gifford said from the AAA Carolinas office in Charlotte, N.C. Gifford said that some stations may be totally out of gas, while others may have trouble getting certain grades of gasoline.

"So what motorists see, is a gas station that once had an outage now has gas. They only have it for a day or so, and then they are out again. That will probably continue until more refineries are back up and operating," Gifford said.

She said such spot disruptions probably will continue for some time.

"We hope that within a week or so, things will get better," she added.

But Gifford said the good news is that gas prices in both states are slowly decreasing, at about a penny or so a day.

The spokeswoman said the average price of a gallon of regular unleaded in South Carolina is now $3.87. The average in North Carolina for the same grade is $3.93, down two cents from Sunday's level.

Nationally, gas prices have fallen five days in a row, Gifford said.

 Gas prices spiked after hurricanes Ike and Gustav caused oil rigs and refineries along the Louisiana coast to shut down or curtail operations, which temporarily diminished deliveries in the Southeast.

On Sept. 15, AAA reported that the average price of a gallon of regular unleaded reached $4.085 in North Carolina and $4.121 in South Carolina.

In Raleigh, Attorney General Roy Cooper's office said the owners of three more gas stations have been subpoenaed in an investigation of possible price gouging.

The stations, one in Charlotte and two in Yadkinville, reportedly charged between $4.49 and $5.35 per gallon, a statement by Cooper's office said. The retailers have 10 days to provide documentation to Cooper's office about their prices.

Subpoenas were sent to owners of 23 other gas stations last week, the statement said.

"We appreciate consumers' help in keeping an eye out for gas gougers," Cooper said. "We're also asking consumers to do their part by conserving gas."