Simultaneous power outages have struck number of major US and Canadian cities, but terrorism has been ruled out by the US government.
Power outages were reported in the New York metropolitan area, Detroit and Cleveland, as well as in Toronto and Ottawa.
CNN reported a fire at a Con Edison power plant in Manhattan. The Oyster Creek nuclear power plant in Forked River, New Jersey was not functioning.
A spokesman for the US Department of Homeland Security said they did not know the reason for the power outages, but there was no indication of terrorism.
New York Port Authority Police said the power outage that is crippling the city has shut down many transportation services.
"Right now the power outage is affecting all of our operations, We have no buses, no trains, no subways running. The airports have their perimeters secured and I can't say right now if flights are coming in or out," a spokesman said.
Thousands of people are stranded underground in darkness in New York's subway system, according to CNN.