The worst blackout in American history may soon be over -- but only because the sun is rising over the estimated 50 million people who were plunged into darkness when power was knocked out over a huge swath of the Northern United States and Canada.
Among the cities that lost all electrical power Thursday afternoon were New York City, Cleveland, Detroit, Toronto and Ottawa. The sudden shutdown of the power grid drove millions of people outdoors into stifling streets and trapped countless others in elevators and subways.
Traffic lights went out, snarling traffic throughout the cities. There was at least one death -- a Long Island resident whose respirator failed.
New Yorkers were trapped, sweltering underground in dreadfully hot subways on a day when the temperature hit 91 degrees. The famed Manhattan skyline was eerily dark.
"We all are wondering what caused this," said New York Gov. George Pataki.
There were reports of "serious looting" in Ottawa, but several officials there downplayed the looting as isolated events.
In Michigan, nearly all of DTE Energy's 2.1 million customers lost power, and the company's chief said it would be a couple of days before the majority had power restored.
"This is truly one of the instances where we're all in this together," Gov. Jennifer Granholm said Thursday night. "So be calm, be supportive of your neighbor."
Very slowly, electricity was slowly returning throughout the affected area -- small consolation for the millions who spent the night without water pressure and air conditioning. There were reports that, by 4:30 a.m. EDT, traffic and street lights were visible in parts of New York's midtown.
Lights flickered on and air conditioners restarted for some, but millions of others baked in stuffy rooms.
President Bush, in San Diego, said the administration had ruled out terrorism as the cause of the blackout. The FBI and Homeland Security Department both said the outages appeared to be a natural occurrence and not the result of terrorism.
"Slowly but surely we're coping with this massive, national problem," Bush said, adding that he would order a review of "why the cascade was so significant."
The president said he suspected the nation's electrical grid would need to be modernized.
New York Mayor Michael Bloomberg said the water supply was safe and that there were no reports of any injuries in skyscrapers or the subways. He said there were no significant fires and "no criminal activity of any size."
The mayor suggested that New Yorkers consider taking Friday off.
"Treat it like a snow day," he suggested. "Look out the window and listen to the radio. It wouldn't be the worst thing to take a day off."
In Cleveland, the loss of power wasn't the only problem. About 1.5 million residents faced a crisis because there was no electricity to pump water from Lake Erie. At least three Eastern suburbs were out of water and officials said Western suburbs could go dry.
About 540,000 customers in Ohio were without power, mostly in the Cleveland area.
In five Northern New Jersey counties about 300,000 customers were without power but in eight others, the number dropped below 1,000.
In New Haven and Bridgeport, Conn. where 30,000 customers had been without power, the number dropped to 1,500.
But in New York, where early estimates had 80 percent of the state without power, the percentage only dropped to some 60 percent near midnight.
Despite the outages in Manhattan, New York's financial markets had no intention of shutting down.
The American Stock Exchange, New York Stock Exchange and Nasdaq reported minimal interruption after the close of trading. All had backup power generators and said they planned to open Friday.
However, businesses from Manhattan through the Midwest were anxious about technical glitches and more power outages a day after the biggest blackout in U.S. history.
Early in the morning, it was still unclear exactly what triggered the massive power outage.
The New York Independent System Operator, which runs the state's wholesale electricity market and monitors power usage, said in a statement after midnight that it detected a fault west of the Ontario power system at 4:11 p.m. EDT.
The ISO did not release details of how or specifically where it detected the fault, and a spokesman did not immediately return calls seeking comment.
At one stage, Canadian authorities said it appeared lightning had struck a power plant on the U.S. side in the Niagara Falls region, setting off outages that spread over 9,300 square miles, but U.S. officials quickly disputed that.
"We have been informed that lightning struck a power plant in the Niagara region on the U.S. side," said Jim Munson, speaking for Canadian Prime Minister Jean Chretien.
But Brian Warner of the New York Power Authority said its Niagara facilities were not hit by lightning and "at no time during this incident ceased to operate."
The blackouts started shortly after 4 p.m. EDT, engulfing most of New York state and nearby parts of New England, and spreading west to Ohio and Michigan. In Toronto, Canada's largest city, workers fled their buildings when the power went off. There also were widespread outages in Ottawa, the capital.
Power began to come back as evening wore on, but officials said full restoration would take much longer. Officials in Detroit urged people to stay home during the night; nearby communities declared curfews to keep problems to a minimum.
By Friday morning, New York authorities had electricity back on in parts of the Bronx, Westchester County, most of Staten Island, portions of Manhattan, and Long Island. About half of the one million homes and businesses that lost power in New Jersey had regained power.
New Yorkers scrambled down endless stairways in skyscrapers where elevators stopped working, and some subway commuters were stuck for several hours underground. In the city that took the brunt of the Sept. 11, 2001, terrorist attacks, people filed into the streets with little fuss and looked for ways to get home.
"I'm trying to keep calm," said Aaron David, 27, who works at the United Nations. "But I was here for 9/11. This doesn't happen every day."
Traffic lights were out throughout downtown Cleveland and other major cities, creating havoc at the beginning of rush hour. Cleveland officials said that without the power needed to pump water to 1.5 million people, water reserves were running low.
New York state lost 80 percent of its power, said Matthew Melewski, speaking for the New York Independent System Operator, which manages the state power grid. Both New York and New Jersey declared states of emergency.
As darkness fell, city dwellers turned to candles and flashlights, people gobbled ice cream from street vendors before it melted, and chugged beer before it got warm, and gathered around battery-operated radios for updates.
Su Rya, 69, in batik shirt and shorts, guarded a store on 125th Street in Harlem. But when asked about talk that looting might break out, he said, "That's barbershop talk. It's a different generation now."
Marveled another man, "You can actually see the stars in New York City."
There were outages in several Vermont towns and in Northern New Jersey, where Gov. James E. McGreevey mobilized 700 National Guardsman and ordered 300 extra state troopers on duty. In Connecticut, Metro-North Railroad service was knocked out. Lights flickered at state government buildings in Hartford.
Broadway shut down. Night baseball, too.
The Mets were trickling out for batting practice in New York when the blackout hit and their game with the San Francisco Giants was canceled. Hours later, the Giants were still waiting in the parking lot for a bus that would take them out of town. Some 500 miles west, the Toledo Mudhens' International League game with the Norfolk Tides was called off, too.
There were no games scheduled in the other hard-hit Major League cities. The Cleveland Indians, Detroit Tigers and Toronto Blue Jays were all out of town.
In Albany, N.Y., several people were trapped in elevators in Empire State Plaza, but most had been freed by 5 p.m. People in New York City lined up 10 deep or more at pay phones, with cell phone service disrupted in some areas. Times Square went dark.
In Cleveland, Olga Kropko, a University Hospitals labor and delivery nurse, said the hospital was using its backup generators and had limited power. "Everyone is very hot because the air conditioning is off," she said. "Our laboring moms are suffering."
John Meehan, 56, walked down 37 stories in the BP Tower in downtown Cleveland, wearing his suit and carrying a briefcase. "It makes you wonder, was this terrorism or what?" he asked.
Police in Mansfield, Ohio, spread into the streets to keep traffic flowing. "A lot of officers are out there trying to make sure nobody gets hurt, to try to cut down on the accidents," said jail officer Randi Allen.
The blackouts easily surpassed those in the West on Aug. 10, 1996, in terms of people affected. Then, heat, sagging power lines and unusually high demand for electricity caused an outage for 4 million customers in nine states.
An outage in New York City in 1977 left 9 million people without electricity for up to 25 hours. In 1965, about 25 million people across New York state and most of New England lost electricity for a day.
On Thursday, Amtrak suspended passenger rail service between New Haven, Conn., and Newark. Some northbound trains from Washington — a city that did not lose power — turned around at Newark.
Pataki urged New Yorkers to make do with less electricity when it returns. "Tomorrow is going to be a very tight energy day, obviously," he said. "We don't want people to think just because the lights are on they can use the washing machine."
As for the cause, he said: "It was probably a natural occurrence which disrupted the power system up there and it apparently for reasons we don't know cascaded down through New York state over into Connecticut, as far south as New Jersey and as far west as Ohio."
Nine nuclear power reactors — six in New York and one each in New Jersey, Ohio and Michigan — reported they were shut down because of the loss of offsite power, according to the Nuclear Regulatory Commission in Bethesda, Md.
The blackout set off security precautions developed after the World Trade Center attack, with heavily armed teams of counterterror officers deploying at New York City landmarks and other sensitive locations.
Officials swiftly realized the outage was not an act of terror and then used teams to make sure no one took advantage of the blackout to strike at a terror target, officials said.
Flights at six airports — Kennedy, La Guardia, Newark, Cleveland, Toronto and Ottawa — were grounded, according to the U.S. Transportation Department.
In Times Square, Giovanna Leonardo, 26, was waiting in a line of 200 people for a bus to Staten Island.
"I'm scared," she said. "It's that unknown `what's going on' feeling. Everyone's panicking. The city's shutting down."
The blackout closed the Detroit-Windsor Tunnel, which 27,000 vehicles use daily, and silenced the gambling machines at Detroit's Greektown Casino. Patrons filed into the afternoon heat carrying cups of tokens.
The Associated Press contributed to this report.