Updated

Lights came back on Friday across a swath of central Canada after the biggest outage in North American history, but travel was still disrupted and people were asked to use as little electricity as possible.

Prime Minister Jean Chretien (search), in his first statement since the Thursday outage, said he would speak to President Bush about it later Friday. But he struck a different tone than officials had early in the outage, when the two sides traded blame.

"Everyone affected by the blackout should be gratified by the close level of cooperation of their governments," Chretien's statement said.

Earlier, Defense Minister John McCallum (search) said Canadian and U.S. security officials will review what caused the huge blackout to examine how to protect against future outages.

He said Deputy Prime Minister John Manley and U.S. Homeland Security Director Tom Ridge (search) spoke after the blackouts and "discussed the need for an early review of the circumstances of this event in the context of our common and national security objectives."

Police in Toronto and Ottawa, the capital, reported looting and other crime during the night of darkened streets, and authorities advised people to stay home if possible Friday.

Ontario Premier Ernie Eves (search) said electricity generation was at 50 percent capacity Friday morning and expected to reach two-thirds capacity by the end of the day.

Eves declared a state of emergency in Ontario, Canada's most populous province. The blackout hit the southern part of Ontario, where most of its 10 million residents live.

Still, Canadian cities appeared to handle the sudden disruption with relative calm, much like New York and other affected U.S. cities.

Many people walked home Thursday night after subway and street-car service stopped working. Some acted as impromptu traffic cops at snarled intersections.

On Friday, downtown streets were filled with people heading to work or taking a day off.

Laurie Koss, 46, a computer technology worker for CIBC bank, said she was happy to go to her air-conditioned office on a day when temperatures reached 86.

"I'm tired, but we just have to get on and deal with it," she said.

In Toronto, police made 38 arrests overnight and reported 114 cases of looting, theft and other crime linked to the blackout, Constable Mike Hayles said. The city fire department received more than 1,400 calls, with five substantial fires reported.

Ottawa police reported two deaths possibly attributed to the outage — a pedestrian hit by a car and a fire victim.

The blackout meant serious delays for travelers, with Air Canada (search) canceling all flights until mid-afternoon Friday after its Toronto operation center lost emergency power.

"The situation is still somewhat fragile," airline spokeswoman Laura Cooke said of the problem at Canada's biggest airport. "The operation system is here in Toronto but it affects flights across the system."

In Sudbury, Ontario, 210 miles north of Toronto, more than 100 miners at a nickel mine spent the night in underground lunchrooms because the outage stopped elevators. They were brought to the surface when power was restored Friday morning.

Ontario Hydro official Al Manchee said the utility would use rolling blackouts throughout Friday to prevent surges as power is restored, while Eves said factories and businesses that use lots of electricity were asked to remain closed Friday to ease the demand.

Officials also pleaded with people to conserve electricity.

"Power conservation remains critical," said the province's public safety and security minister, Bob Runciman. "It's absolutely vital that everyone do their part to save energy and help the province through this emergency."

Toronto Mayor Mel Lastman (search) said people should avoid using air conditioners or dishwashers, and urged everyone to get a flashlight rather than relying on candles because of the fire risk.

In the hours of confusion after Thursday's outage, Canada's government offered conflicting explanations for the blackout, insisting it started south of the border. U.S. officials and power industry figures initially blamed Canada, then said Friday they are focusing on a massive electrical grid that encircles Lake Erie.

McCallum had blamed a fire at a nuclear plant in Pennsylvania but then backed away from that claim. He said Friday that no one knows exactly what happened — but insisted whatever it was, it happened in the United States.

"The Americans don't have all the answers," he said. "The origin of the problem is in the United States, and the United States doesn't have all the answers."