Electric companies from around the country began rushing crews to the hurricane-ravaged South on Tuesday to help restore power to an area so devastated that it could be weeks or even months before the lights come back on in many places.

"It's catastrophic. Working conditions are hazardous. It's hot and humid," said David Botkins, a spokesman for Dominion Virginia Power (search), which sent 200 workers to Louisiana and Mississippi. "The entire grid system in these areas is completely ruined. They're starting from scratch."

Katrina hit the Gulf Coast on Monday, packing winds of 145 mph, killing dozens of people and swamping thousands of homes in one of the most punishing storms on record in the United States. Nearly 2 million customers were without power Tuesday in Louisiana, Mississippi, Alabama and the Florida Panhandle.

"It looks like it's going to be a massive undertaking," said Jim Owen, spokesman for Washington-based Edison Electric Institute (search), a group of 200 investor-owned power companies.

In a mutual aid arrangement, companies are sending workers by the dozens and the hundreds to assess damage, erect power poles, put up lines, clear debris, trim trees and arrange food and housing for fellow workers. A caterer volunteered to accompany 125 workers from Tampa Electric Co. (search) who headed to Baton Rouge, La., on Tuesday.

Columbus-based American Electric Power Co., the nation's largest power generator, has dispatched 1,000 workers and contractors from its operating companies, topping the 800 it sent to Florida last year to help after Hurricane Jeanne. North Carolina utilities contributed at least 1,800 workers, with some being told they will be gone at least two weeks.

"We're sending all the folks we can spare," said Melissa McHenry, an AEP spokeswoman.

Some utilities already had workers in Florida, where Katrina knocked out power to 1.45 million customers last week, and may send them to other stricken states. Other companies were holding back workers in case of outages as the hurricane dumps rain and possibly produces tornadoes as it moves north and east.

"We need to make sure we have enough people to keep the lights on in New Jersey," said Karen Johnson, spokeswoman for Public Service Electric & Gas, New Jersey's largest utility.

The full extent of the damage wasn't yet known. Flooding kept crews from getting to some areas. The floodwaters will need to be drained before power crews can start to work.

"We're so early in the storm ... that the hometown companies only themselves are in the early stages of identifying where the damage is," Owen said.

The utilities that need help pay the bill.

In disasters, utilities concentrate first on repairing transmission lines and substations. Then crews restore power to police and fire stations, hospitals, sewage pumping stations and shelters before moving on to the areas where power can be restored to the largest number of people in the shortest time.

The tradition of utilities helping each other during major outages dates back decades. Utilities in the South, for example, sent workers to Ohio to restore electricity in December when an ice storm knocked out power to 275,000 homes for a week or longer.