TORONTO (AP) _ Canadian officials blamed a massive blackout Thursday across the Northeast and parts of Canada on a lightning strike at the Niagara power plant, but officials there denied it.
``We have been informed that lightning struck a power plant in the Niagara region on the U.S. side,'' said Jim Munson, a spokesman for Canadian Prime Minister Jean Chretien.
Brian Warner of the New York Power Authority said he wasn't sure where the power failure originated.
``The New York Power Authority's Niagara Power Project has at no time during this incident cease to operate. We also have not experienced a lighting strike at that facility,'' he said.
U.S. officials said they were looking at a power transmission problem from Canada as the most likely cause of the biggest outage in U.S. history, said a spokeswoman for New York Gov. George Pataki. There was no sign of terrorism, officials in New York and Washington agreed.
In Canada, blackouts were reported in Toronto, as well as Ottawa in the province's eastern reaches and in much of Ontario. The blackout had not spread as far as Thunder Bay in northwestern Ontario, suggesting power in the north was sporadic.
Power was also knocked out on Parliament Hill, leaving scant emergency lighting.
In Toronto, streetcars preparing to transport workers around downtown for the evening rush hour ground to a halt, sending riders into the street to hail taxi cabs.
Some people ended up directing traffic on their own.
Wearing a suit and tie, Peter Carayiannis waved vehicles through one busy intersection. ``I've been doing this for about 45 minutes because nobody else is,'' he said.
``The streetcar can't go anywhere, you just have to wait,'' said Mike Collins, a streetcar driver with the Toronto Transit Commission.
Diane Grover, spokeswoman for the Canadian defense department, said Canada ``considers this an act of nature in the Niagara region on the U.S. side of the border. It has caused a cascading power outage affecting 9,300 square miles,'' she said.
Grover said the power company, Ontario Hydro, was in the process of separating itself from the American power grid in order to restore electricity to its customers.
An official at the Ontario power company agreed, saying the problem originated elsewhere.
``We're confident that the trigger for this widespread outage did not occur on our system,'' said Al Manchee. ``There was no indication that there was anything wrong in our system prior to the outage.''
He said power was being restored slowly, with substantial progress expected throughout the evening.
Toronto's international airport was one of six, including airports in New York, Newark, Cleveland and Ottawa that was grounded, according to the U.S. Transportation Department.
Millions of Canadians were without power, and the total blackout area covered roughly 50 million people. Electricity was out in a broad swath of the Northeast _ stretching west to Ohio and Michigan _ and in southern Canadian cities, starting shortly after 4 p.m. EDT.
Power began to come back in some cities as afternoon turned to evening, but officials said full restoration would take much longer.
