From the Midwest to Manhattan Friday, areas stricken by a massive blackout struggled back to normalcy as power was restored to millions of people.

Nonetheless, many regions faced a new host of problems: Ohio endured the worst water crisis in its history; rolling blackouts plagued upstate New York, knocking out power that had recently been restored; and in Detroit, drivers awaited an emergency shipment of nearly 1 million gallons of gas.

In one positive development, Consolidated Edison announced that all power was restored to New York City at 9:03 p.m., just under 29 hours after the outage struck.

"We are 100 percent back," said Con Ed spokeswoman Joy Faber said. "Hundreds of employees are working around the clock and will continue to work through the weekend to stabilize the system and to try to prevent any further disruptions."

Three deaths were linked the blackout, which knocked out service in parts of eight states and Canada in a mere nine seconds.

• Photo Essay: Lights Out

Meanwhile, the cause of the worst outage in U.S. history continued to elude experts. Investigators focused on a massive electrical grid that encircles Lake Erie (search), shuttling power from New York to the Detroit area, Canada and back to New York state. There had been problems with the transmission loop in the past, officials said.

"We will find out what caused the blackout and we'll deal with it. This was a wake-up call … for the need to modernize our electricity delivery systems," President Bush said from California Friday on a trip promoting his national park system. "The people in New York and in the Northeast and in the Midwest showed the great character of America under very difficult circumstances."

Canada and the United States formed a joint task force Friday to investigate what caused the blackout and how to prevent it from happening again.

Although many people immediately suspected terrorism, an attack was quickly ruled out by Bush and other officials.

But the North American Aerospace Defense (search) command scrambled two Air Force F-16 fighter jets to patrol the skies between New York and Washington as a precautionary measure. NORAD also put other aircraft on alert in eastern U.S. bases.

"I doubt the response would have been as good prior to Sept. 11," Bush said.

Homeland Security officials said all resources and available assets under their control were ramped up to be deployed Thursday night, but as of 1 p.m. Friday, no request — except one for a generator for New York City — were made, Bush said.

In New York City, Mayor Michael Bloomberg said he received a call from Bush offering congratulations on the city's handling of the crisis. Crime in the city was actually down overnight compared to an average evening, he said.

"I think all New Yorkers have done their part," Bloomberg said. "If we compare this time to what happened in 1977, when there was chaos and crime, this time we saw compassion."

But while the outage may not have sparked civil unrest, it paralyzed New York's crucial subway system and the two major commuter rail lines. The city's subways, which carry 5 million daily riders, won't return until at least Saturday, Bloomberg said.

New Yorkers endured an outage longer than the 25-hour blackout of 1977.

Video: New York Mayor Mike Bloomberg

In Ohio, most of the 1.4 million people affected by the blackout regained power by Friday afternoon. Nonetheless, Cleveland struggled mightily to provide residents with water for simple tasks like brushing teeth. There was not enough water pressure to create more than a trickle from taps.

The restoration of power was merely a tease for an unlucky swath of New York, where the electricity crackled and then quickly ceased. Upstate utilities — shortly after restoring power — were ordered to initiate rolling blackouts as a conservation measure, with as many as 50,000 customers affected.

"This is the crisis of a career for me," said Julius Ciaccia, Cleveland water commissioner, a 27-year employee. Cleveland officials, fearful of sewage flowing into Lake Erie because of the outage, closed the city's beaches.

In Connecticut, residents heard an emergency plea from the governor to cut back on power use after a state transmission line that feeds the southwest part of the state failed early Friday.

The call for conservation echoed across each state affected by the blackout. "Every light bulb matters today," said Long Island Power Authority (search) Chairman Richard Kessel. "If you don't turn them off, they will go off."

Despite plunging several of the nation's largest cities into darkness, the outage resulted in few reports of vandalism or increased violence. But there was at least one U.S. fatality: A 40-year-old New York man suffered a heart attack during an overnight fire.

In Canada's capital of Ottawa (search), police reported 23 cases of looting, along with two deaths possibly linked to the blackout — a pedestrian hit by a car and a fire victim. There were also reports of minor looting in Brooklyn and Detroit.

Officials in Michigan also blamed the power failure for a small explosion at a refinery about 10 miles south of Detroit. No injuries were reported, but hundreds of residents within a mile of the refinery were evacuated.

Officials warned Michigan residents that air conditioning and television could be out of commission until the end of the weekend.

While remained in the dark about the origin of the outage, they did not refrain from assigning blame.

Initial reports cited a lightning strike near Niagara Falls, followed by fingerpointing at Ohio, where officials pointed back at Canada and upstate New York. On Friday, one expert speculated the problem began in Michigan.

Bloomberg and Gov. George Pataki encouraged the locals to treat Friday as a 90-degree snow day — stay home from work and relax.

To reinforce their point, all state parks and beaches were open to the public for free. Pataki also demanded an investigation into what he called failures to improve the regional power system and prevent blackouts like those of 1965 and 1977.

"We have to know why this happened, how it happened," he said.

Cleveland workers were advised to stay home until noon on a day when temperatures climbed into the mid-80s. A few ignored the advice, strolling through near-empty streets.

"I have no water and no lights so I might as well come to work," said attorney Lori Zocolo, arriving at her downtown office at 5:30 a.m. in a T-shirt and shorts. Her biggest complaint: No water meant she couldn't brush her teeth.

Power was switched on Friday at the four pumps that provide water to 1.5 million people in Cleveland and its suburbs. Still, bottled water became a precious commodity in Ohio, and two dozen National Guard tankers began distributing emergency drinking water.

In Detroit, low water pressure had officials warning residents to boil water before drinking or cooking with it. The failure of electric pumps led to a run on gasoline, with Detroit residents lining up to fill their containers.

Michigan Gov. Jennifer Granholm (search) signed an executive order to expedite nearly 1 million gallons of gasoline from western Michigan to the Detroit area.

Flights resumed Friday morning at Cleveland Hopkins International Airport as the airline business slowly returned. But despite the airlines' efforts, hundreds of flights were canceled nationwide.

At the New York area airports — Kennedy International, LaGuardia and Newark Liberty — planes were arriving and departing, but with unspecified delays. About 3,000 people were stranded overnight at Kennedy.

"They're trying to catch up," FAA spokeswoman Laura Brown said of the airlines.

Fox News' Bret Baier, Alisyn Camerota, Mike Emanuel and The Associated Press contributed to this report.