Hurricane Irene knocked out power to 2.5 million homes and businesses, forced two nuclear plants to shut and idled oil ports and refining as it advanced toward New York City early on Sunday.
Mid-Atlantic coast states reported more power losses even as the hurricane spun northward and blackouts in Delaware, New Jersey and New York jumped.
The category 1 hurricane made landfall in New Jersey before dawn with 75 mile-per-hour 120kph winds, dumping heavy rain and provoking storm surges.
In New York City, more than 70,000 customers had power outages. Consolidated Edison, which powers nearly 3 million homes and businesses in the city, warned that flooding could prompt wider power cuts in downtown Manhattan.
Two East Coast nuclear power plants shut to ensure safety. Aluminum siding flew off a building in Maryland and slammed into a transformer at CENG's Calvert Cliff reactor early Sunday, forcing it to shut. The plant declared an "unusual event," or low-level emergency, but said the reactor was safe.
As a precaution against winds, Exelon Corp took its Oyster Creek nuclear power plant in New Jersey offline on Saturday. The plant normally supplies electricity to as many as 600,000 homes.
Several East Coast oil refineries throttled back operations and ConocoPhillips shut its Bayway plant in New Jersey.
With gale-force winds and rough seas threatening shipping, the oil hubs of New York Harbor and the Port of Philadelphia declared alert level "Zulu," an emergency designation that severely restricts vessel traffic, the US Coast Guard said.
The path of Irene was shifting westward, raising the prospect of 10-foot(3 metre) storm surges, forecasters said. That could raise the odds of blackouts in New York City.
Con-Ed said it was evaluating whether to turn off power later on Sunday in low-lying areas of Manhattan including the Financial District. Hundreds of thousands of residents have already evacuated to higher ground.
"We're now at a critical moment of the storm with debris starting to fly due to the high winds," said Con-Ed spokesperson Joy Faber. "Our crews in the field are reporting more hazardous conditions."
Shutting off power in downtown Manhattan before flooding from a storm surge could lessen the time required to restart services.
Irene earlier cut power to large swaths of Virginia and North Carolina as it came ashore, prompting Brunswick nuclear power plant in Southport, North Carolina to reduce power generation.
