Hurricane Sandy plunged much of lower Manhattan into darkness, leaving most of the island south of 39th Street without power hours after the storm made landfall.
About 230,000 Con Edison customers in Manhattan lost power, and nearly 400,000 more customers in the outer boroughs and Westchester County were in the dark, Con Ed officials said.
The blackout Sandy caused is one of the five largest in New York City history, and the largest ever caused by a storm, said John Miksad, Con Ed's senior vice president of electric operations.
"This will be the one for the record books," Miksad said.
Residents in Manhattan could be without power for at least three or four days, he said.
"We've got to get in there, assess the damage and work on a restoration strategy," Miksad said. "if push came to shove, it could be up to a week, but I'd anticipate both Staten Island and Manhattan to be sometime before that."
Con Ed spokesman Bob McGee said more outages can be expected.
"As long as we've got 70 mph winds and sustained winds from 45 to 60 mph, and another peak high tide at 8 a.m., when we have these kinds of conditions, it's all problematic," he said.
In all, Sandy left about six million people across the Northeast without power.
Most of lower Manhattan lost power just after 9 p.m. Monday, when a transformer line exploded at Con Ed's East 14th Street substation. The explosion was probably caused by flooding or flying debris, Miksad said.
Con Ed's Leonard Street substation also suffered significant flooding. Con Ed was expecting flood levels between 10 and 12 feet, but 14-foot tides overwhelmed the system. Some people on the southwest tip of Manhattan and far West Side still had power.
"This storm has lived up to its billing, in terms of being very dangerous and also creating a lot of havoc," McGee said. "It's pretty much done what we expected."
Derek Ingber, a TV producer who lives on 14th Street, said he faced total blackness in a neighborhood that had already dealt with the facade being blown off an apartment building earlier in the night.
An email from Con Ed warned her and her neighbors that power would likely be shut down, giving her time to let her family know and charge cell phones. She said neighbors gathered in the hallway in their pajamas to help one another.
"It was sort of like a camaraderie moment," Avery said.