Surrounded by darkness with daylight trickling in through the front windows, Paul Moock sat at a desk inside Outdoor Power Equipment, wearing a winter coat.

The only electricity came from a generator powering a few computers and telephones at the retail and service shop at the Roanoke Salem Business Center on Melrose Avenue in Northwest Roanoke.

It was one of the many Roanoke Valley businesses without power Monday, though the store was busy trying to help customers restore heat and electricity in their homes.

By midday Monday, the retailer had sold at least a dozen generators, and inventory was growing low.

"When they hear that power will be off until Thursday, it makes them a little nervous," Moock said of the customers who came to buy generators priced from $799 to $3,500.

Moock, co-owner of Outdoor Power Equipment, said he planned to keep the store open all day, even if the power did not come back on.

"We've been busy enough today to stay warm," he said, adding that he planned to replenish his stock.

Generators and other emergency heating devices, such as kerosene heaters, were scarce or sold out at hardware and equipment stores throughout the Roanoke Valley after strong winds cut off power to more than 80,000 Virginia residents and outside temperatures hovered in the 30s.

Appalachian Power Co. said that some Roanoke area customers could be without power until Thursday or Friday.

Northwest True Value Hardware's Williamson Road location sold six kerosene heaters in 30 minutes Monday. By 10 a.m., it had sold out of kerosene heaters, and owner Charles Overstreet already had ordered a new supply.

"I'm hoping they will get here early" today, he said.

Faye Kahn of Roanoke was frustrated when she walked into Northwest Hardware at 11:15 a.m. to find no kerosene heaters. She began her hunt for quick heat about 8 a.m., first checking Home Depot and Wal-Mart. Both stores were sold out, she said.

She gazed at Northwest's selection of space heaters, including an infrared gas heater for $179 and a propane heater for $119.

Kahn's home had been out of electricity since 2:30 p.m. Sunday.

"We went to bed early last night," she said, turning to leave the store.

By Monday morning, Northern Tool & Equipment Co. in Salem had sold "somewhere between 50 and 100" generators, according to assistant manager Jeff Gruver.

"Generators have been really going out the door this morning."

Units ranged from about $499 to $3,000, he said. Generators with sufficient wattage to run a refrigerator and a few other appliances cost about $1,200 to $1,400, Gruver said.

Northern Tool & Equipment has ordered additional units, he said.

Buyers should expect to serve only a portion of a home's electrical needs with portable generators. According to Cornell Cooperative Extension, selecting a portable generator for household needs "requires a decision about what electric circuits are really necessary during a prolonged outage."

A 4,000-watt to 6,000-watt portable generator could be adequate to run a furnace, operate a refrigerator, pump water and power a few lights, the extension reported.

According to a Honda generator chart, operating a 650-watt microwave oven requires about 1,000 watts.

Lewis Porterfield studied the generators displayed on the largely bare shelves at Northern Tool & Equipment on Monday afternoon.

The Botetourt County resident was seeking a generator to save the perishable foods in his refrigerator. But after seeing the prices, he changed his mind about the purchase.

"I could restock my refrigerator several times," Porterfield said.

Staff writer Duncan Adams contributed to this report.