DETROIT (AP) -- Thousands of Michigan residents woke up without power Friday and the possibility that it wouldn't be restored anytime soon, while Cleveland, also darkened by the sweeping blackout, faced its worst water crisis in history.
The massive outage, which spread in minutes Thursday through the northeastern United States and southern Canada, also caused an explosion at the Marathon Oil refinery about 10 miles south of Detroit.
No one was injured in the blast, but police, fearing another explosion or possibly toxic gases, evacuated one mile around the 183-acre complex, sending hundreds of residents to seek shelter elsewhere.
Fire officials said the lack of power caused a buildup of gasses and ultimately triggered the explosion in one of the smoke stacks at the facility which produces gasoline as well as jet and other fuels.
In Ohio, power was restored to much of downtown early Friday, but the city still had a long way to go to bring water back to a million residents.
The blackout knocked out all four major pumping stations for first time in Cleveland's history. All four were operating Friday morning and most of the secondary stations were up, Mayor Jane Campbell said, but she could not estimate when the first of those without water would see their taps flowing.
The National Guard was bringing in tankers Friday to distribute more than 7,600 gallons of drinking water.
Attorney Lori Zocolo, who still hadn't had a chance to brush her teeth, walked to her office at 5:30 a.m. wearing a T-shirt and shorts -- but carried a business suit under one arm just in case.
She heard on the radio on her way in from Cleveland Heights about the mayor's wishes for workers to stay away from the city until noon, but that didn't stop her.
"I have no water and no lights so I might as well come to work," Zocolo said.
At its peak Thursday, the blackout left 1.4 million FirstEnergy customers in Ohio without power. About 450,000 were still without power early Friday, spokesman Ralph DiNicola said. He said power should be fully restored by Friday.
In Michigan, where some 2 million customers were without power at the blackout's peak, Gov. Jennifer Granholm said it may take all weekend to restore all power. Consumers Energy, which serves 1.7 million customers in the lower peninsula, said early Thursday that it had nearly finished restoring power to 100,0000 customers.
"This is truly one of the instances where we're all in this together," Granholm said. "So be calm, be supportive of your neighbor."
Shortly after power failed in Detroit, workers -- some of whom had been trapped in elevators -- streamed from city and state office buildings and gridlock ensued on major roads as they fled to their homes. Patrons of the Greektown Casino filed into the afternoon heat holding cups of tokens, while sirens could be heard in Lansing as the Capitol was evacuated.