Blackouts cause North America chaos
Work has been going on through the night to restore power after massive blackouts hit major cities in the eastern United States and Canada.
The power failures caused chaos as they spread from New York to Detroit, and Toronto to Ottawa. Traffic lights failed, underground railways were evacuated and people were trapped in lifts in offices and apartments.
Canadian officials said a fire at a power plant near the upstate New York town of Niagara caused the outage - at about 1610 local time (2110 GMT) - which then cascaded across the country.
The US Department of Homeland Security said it was investigating the cause of the blackouts but US officials - who dispute the Niagara theory - have said there is no evidence terrorism is to blame.
Power is slowly returning to the affected areas - thought to encompass more than 50m people - but full restoration will take much longer, officials say.
Federal Energy Regulatory Commission spokesman Bryan Lee said the outage destabilised the power grid, cascading up and taking "a loop around the Great Lakes into Canada".
But US officials were looking at a power transmission problem from Canada as the most likely cause of the biggest outage in US history, said a spokeswoman for New York Governor George Pataki.
In other developments:
- There have been reports of sporadic looting in at least four areas of the Canadian capital, Ottawa.
- President George W Bush said the outages were not a terrorist act and added: "We're slowly but surely coping with this massive national problem."
- Nine nuclear reactors in four US states were taken offline, the nuclear regulator said.
- The US Federal Aviation Administration halted flights into six airports, three in the New York area, one in Cleveland, and two in Canada.
- In New York City, subways, lifts and airports, including John F Kennedy and LaGuardia airports, lost electricity or resorted to limited backup power.
- The blackout closed the Detroit-Windsor Tunnel, which 27,000 vehicles use daily.
'No injuries'
Many workers left their offices early, walking across bridges out of Manhattan, choking pavements and roads.
New York Mayor Michael Bloomberg said power was starting to come back from the north and from the west but would take hours not minutes. In an effort to calm frayed nerves, he cautioned New Yorkers to stay cool and drink fluids.
New York emergency services had no reports of anyone injured during evacuations from tall buildings or underground subways.
Power to many hospitals and prisons was also reported to have failed but key institutions were working on back-up generators.
Searing heat
The BBC's Lee Carter, in Toronto, says the lights went back on in the centre of the city just after 2300 local time (0400GMT).
The city's landmark, CN Tower, was once again illuminated, but power is returning very slowly to the city, with most areas still reportedly in darkness.
As in New York, the blackout hit Toronto, Canada's commercial and financial centre, right at the beginning of rush hour. Trams and underground trains in the city came to an abrupt halt.
The situation was made more uncomfortable by the 90F (32C) heat in New York and Toronto. Gabriela Mira, 40, and her six-month-old daughter waited in a long queue to use a public telephone in New York.
"I had to get out of the house," she said. "It was so dark, and everything was off, and I was scared. No air conditioner, the phones - they need electricity. And it's so, so hot."
Other affected cities include Detroit in Michigan as well as Cleveland and Toledo in Ohio and Toronto and Ottawa in Canada. There were reports of outages in New Jersey and Connecticut as well.
