It could take weeks to restore power to millions of people left in the dark by Hurricane Irene.

The lights went out for six million people and businesses, from Folly Beach, S.C., to Portland, Maine. The race to restore power now will hinge on thousands of utility workers.

Getting the lights back on will be an enormous job for repair crews fanning out throughout the East Coast. Irene ripped down power lines and crushed critical equipment near power plants. It flooded coastal cities with seawater, dousing electrical stations and threatening underground electrical wires. Crews are still assessing the damage.

"We're dark across the whole map," said Theresa Gilbert of Connecticut Light & Power. Irene blacked out half of the utility's 1.2 million customers Sunday, making it the worst outage in Connecticut history.

More than five million people and businesses remain without power. Some areas, like Manhattan, were relatively unscathed from the weekend storm while others will need days, or even weeks, to recover.

The outages could be critical for the elderly, the disabled and others who rely on community services.

"What if we're without power for days?" asked Pat Dillon, 52, who is partially paralyzed from a stroke. Dillon's senior care facility lost power when a generator failed. As he sat in the dark, Dillon worried that his wheel chair batteries would run out. Even worse, he needs to keep his diabetes mediation chilled.

"Once the refrigerator gets warm, my insulin goes bad," Dillon said. "I could go into diabetic shock. It's kind of scary."

Power companies say they'll try to get critical services running first. But many are just starting to understand the full extent of damage to the grid. Utility workers must comb through thousands of square miles to find out what's down before they can start repairs.

"It's going to be several days at least for our most severely damaged areas" to get power back, said Mike Hughes, a spokesman for Progress Energy in North Carolina, which serves about 3.1 million customers.

Gilbert, with Connecticut Power, said it took two weeks to restore power after Hurricane Gloria knocked out service to 477,000 customers in 1985.

"And this definitely blows those numbers away," she said.

In Virginia, Irene knocked out power to more than 300 critical services, including hospitals, emergency call centers and fire stations. Dominion Resources expects half of those facilities to be restored by the end of the day and most of the rest fixed by Monday.

Most of those facilities have backup generator, Dominion spokesman Dan Genest said. "For those that don't, we're asking them to take care of their people as well as they can. We'll get them up as soon as possible."

Lights were already flickering back to life in parts of the South, where the storm hit first. Crews have started clearing uprooted trees and reconnecting electrical lines. Power is returning to more than a million homes and businesses in the region. Utilities in southern Pennsylvania, North Carolina, Virginia and Maryland say they've restored power to more than 1.3 million customers as of Sunday afternoon.

"A number of rivers in northern New Jersey are under an extreme flood watch," said Ron Morano, a spokesman for Jersey Central Power & Light. He said the number of outages would keep going up today.

Some of the storm's damage will be easy to spot: a tree smashed into a power pole, for example. Other problems will be tougher to figure out. Sometimes power has been cut off with no apparent damage. That's a tougher situation because crews need to move slowly down power lines, looking for places where there is no electrical current. That can take days.

Power companies will focus on parts of their system where they can restore power to the most people at once. They'll start with massive transmission lines that supply entire counties. Then they'll deal with smashed utility poles that serve individual neighborhoods.

After battering the East Coast on Saturday and early Sunday, Irene weakened and headed toward eastern Canada. Fifteen people from seven states died in the storm.

New York City's biggest power company, Consolidated Edison, said it was optimistic it would not have to cut electricity to save its equipment. The city escaped any vast power outages.

As skies clear, Progress Energy said it is ramping up power to its nuclear generating units in Southport, N.C. and expects to be at full power within 24 hours. The nuclear plant was powered down before Irene hit as a precaution.

Constellation Energy Nuclear Group said one of two nuclear reactors at Calvert Cliffs, Md. went off-line automatically because of Irene's winds. Constellation said the plant was safe.

As they switch off nuclear power plants, the utilities turn to other energy sources like natural gas-fired generators to keep the power flowing to customers.


Chris Kahn can be reached at http://twitter.com/ChrisKahnAP