Updated

Lights and air conditioning were back on in many parts of the Cleveland area Friday following the largest blackout in U.S. history. But hundreds of thousands of homes and businesses remained without power, and there were indications the blackout may have been triggered somewhere along Lake Erie in Ohio.

"That's where the information is starting to point," said Ellen Vancko, a spokeswoman for the North American Electric Reliability, an industry-sponsored group that monitors the transmission system. "It looks like that's where the collapse started."

Vancko said it would take time to pinpoint the cause.

In downtown Cleveland Friday morning, half-illuminated high-rises and a lit-up Jacobs Field, home to the Indians, returned a look of normalcy to the downtown skyline. But street and traffic lights were still dark, lending a sleepy atmosphere to a normally bustling rush hour.

"I have no water and no lights so I might as well come to work," said attorney Lori Zocolo, who arrived at her downtown office at 5:30 a.m. wearing a T-shirt and shorts. She carried a business suit under one arm and said she hadn't been able to brush her teeth.

All four of the city's main water pumping stations failed in Thursday's blackout, but were back in operation along with most of the secondary stations. Water was flowing to some of the city's eastern suburbs, but not to all 1.5 million customers.

Mayor Jane Campbell expected water would be restored throughout much of the metropolitan area by noon. She said low-elevation areas would get water first.

"Within 24 hours of the event happening we will be returned to normal," Campbell said.

Thursday's power outage, which stretched from Detroit to New York and into Canada, threw millions of homes and businesses across northern Ohio into the dark. Flights were canceled, police officers were sent into the streets to direct traffic and generators in prisons and hospitals were kick-started.

Ohio's sole operating nuclear power plant in Perry was shuttered, mass transit was halted and phone service was interrupted. Some 1.5 million residents in greater Cleveland lost water when all four of the city's pumping stations failed.

Several miners were stuck for six hours in the Morton Salt Mine in Grand River when power to the mine elevator went out. The men had enough oxygen and got out safely, officials said.

Lake Erie's beaches were closed for swimming because of a sewage backup.

Gov. Bob Taft declared Cuyahoga County a disaster area and sent National Guard tankers to Cleveland to distribute more than 7,600 gallons of drinking water.

At its peak Thursday, the blackout left 1.4 million FirstEnergy customers without power. About 150,000 were still in the dark Friday morning.

FirstEnergy spokesman Ralph DiNicola said the utility expected to have power restored to all customers on Friday, but rolling blackouts may have to be instituted because of a lack of available power.

James Landers walked briskly to work on Friday, clutching a copy of The (Cleveland) Plain Dealer under his arm bearing the headline "BLACKOUT." Lander was one of the few pedestrians walking the streets.

"It's empty," he said. "It looks like a Sunday."

The blackout spread darkness — and confusion — in 14 counties along a 145-mile stretch of the Lake Erie coastline from Toledo to Ashtabula. Wary residents stocked up on batteries, bottled beverages and canned food. The power outage also prompted a run on generators.

"They're gone," said a busy Gary Arto, a manager at Lowe's in Jackson Township. A Sam's Club Warehouse in Massillon sold 18 generators at $500 each food.

Megan Quinn and her mother, Susan, were among the late-night shoppers at a Giant Eagle supermarket in suburban Westlake, one of the few stores that remained open.

They filled their shopping cart with bottled water and nonperishable food items — enough to last several days. They said they feared there would be a run on the items Friday.

"You've got expect the best, but prepare for the worst," Quinn said.

Crime was up slightly overnight in Cleveland. Police reported 20 to 30 break-ins, twice the amount of a typical summer weekday. Police said at least seven suspects were in custody.

"We have not seen any widespread evidence of looting," Campbell said.

Nurse Jayne Cranmer worked from midnight to 8 a.m. at a Parma nursing home, giving residents medication and taking temperatures by the light of a flashlight.

"We had a lot of the residents in bed by dark," Cranmer said. "Most of the residents were calm. Some of the confused residents were agitated."

The outage hit just as afternoon rush hour began in Cleveland. Cars jammed intersections where traffic signals were out. Buses continued to run. But commuter rail trains were halted in the midst of routes, forcing passengers to get off the electric-powered trains and walk to the nearest depots.

Officials said the commuter train service is expected to be restored by noon Friday.

At the Hampton Inn, general manager Steve Rudolph light up the hotel lobby with his car's headlights. The hotel's emergency lights had long since burned out.

He said he would not charge guests because the downtown hotel was without air conditioning, television and hot water.

Cedar Point amusement park in Sandusky was without electricity, leaving some patrons stuck on rides temporarily. Hospitals lost power but continued to operate on backup generators.

Just before midnight, Gigi Thomas of University Heights dashed out to get bottled water at a Tops grocery store in nearby Beachwood — which to her surprise had electricity — so that she could wash up in the morning.

"I don't understand it. Where I live, it's all dark. We have no water and I tried to drive but it's dangerous because there's not lights on the street and here it's all lit up," said Thomas, 32.

Many outbound flights at Cleveland Hopkins International Airport were canceled as hundreds of passengers waited in hot terminals for air conditioning and other power to be restored. Campbell said flights were resuming Friday morning.

The air traffic tower, runways and other essential functions were under backup power within minutes after Thursday's massive blackout. But airport commissioner Fred Szabo said were still trying to rig up power for security screening and baggage screening.

Some travelers didn't mind the blackout.

"It's weird to see half the buildings on," said Michael Kelly of Virginia Beach, Va., as he gazed at the Cleveland skyline at 5 a.m. Friday. "It was actually pretty neat. I will always remember where I was when the lights went out."