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Power was mostly restored Monday evening in the parts of Toronto affected by a blackout triggered by a fire at a transformer station in the city's west end that left 240,000 Toronto Hydro customers in the dark.

Electricity was restored for all but 1,300 households by 8 p.m. ET, more than three hours after the start of the blackout, Toronto Hydro spokeswoman Denise Attallah told CBC News.

The power outage started around 4:45 p.m. ET on a day when Toronto was under an extreme heat alert, with temperatures rising to 34 C, and caused traffic chaos at the height of the city's afternoon rush hour.

Daffyd Roderick, a spokesman for Hydro One, which supplies power to distributor Toronto Hydro, said the cause of the fire that sparked the failure was still under investigation.

The fire happened at the Manby Transformer Station on Kipling Avenue in the Etobicoke section of Toronto. Hydro One said equipment at the station caught fire and that the cause of the blaze is under investigation. No injuries have been reported at the station, the power company said.

Hydro One lost about 900 megawatts of electricity inside the affected area during the blackout and had to restore all of the big circuits that connect its transformer stations, Roderick said.

Six Toronto Hydro substations fed by Hydro One were out of service as a result of the outage, Toronto Hydro said.

Power was restored through a process called backfilling, which is when hydro agencies draw on other sources of power and re-route the power around the out-of-commission transfer station to get it to customers, the CBC's Muhammad Lila reported.

"Hydro One has told us that pockets of power are going to be coming and going," he said.

Both Hydro One and Toronto Hydro urged customers to conserve energy and unplug major appliances such as air conditioners to avoid overloading the system.

The blackout brought back memories of the massive one in August 2003 when 50 million people from New York to North Bay, Ont., were left in the dark after several power grids went down. It was the largest blackout in North American history.

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Commuter chaos

A map posted on the Toronto Hydro website soon after the outage showed large swaths of the city had been affected. The area where outages occurred stretched from Renforth Drive in the west to Yonge Street in the east, and from the Gardiner Expressway in the south to Highway 401 in the north.

The blackout disrupted many commuters, with subway service down from Jane to Kipling stations on the Bloor-Danforth line and minor delays reported along the Yonge-University-Spadina line at Union Station.

By 7:30 p.m. ET, subway service, which had been replaced by shuttle buses, was restored, Toronto Transit Commission (TTC) chair Adam Giambrone said.

Streetcars and buses although still running were delayed during the blackout because of the many downed traffic lights.

At the height of the outage, stranded commuters filled the streets as police — and sometimes pedestrians — directed traffic.


A pedestrian speaks to a Toronto police officer while directing traffic during a power outage in Toronto on Monday. ((Peter Jones/Reuters))

Pedestrian Aseel El-Baba took it upon herself to direct traffic at King and Wellington streets in downtown Toronto for about an hour before police arrived.

"I saw two near car accidents, and I thought, 'OK, I have to do something'," she told CBC News. "The first five minutes were scary, but I got used to it."

Police told her she was a safety risk and urged her to leave the intersection, she said.

The power went out briefly at Pearson International Airport, but the airport authority's website showed few flight delays.

Capt. Mike Strapko of Toronto Fire Services said firefighters had to rescue some people who got trapped in elevators when the power failed.

Giant fireball reported

Stephen Michalowicz of the local news website Torontoist reported seeing a "giant fireball" near the Kipling Avenue facility.

Queen Elizabeth and the Duke of Edinburgh attended a state dinner at the downtown Royal York Hotel, which was among the buildings that lost power. The 7:30 p.m. dinner, hosted by Prime Minister Stephen Harper, proceeded despite the outage.

Prince Philip was presenting the Duke of Edinburgh Awards, a program that encourages youth to participate in community service, among other areas, when the lights went out. But the emergency power kicked in at the hotel and he handed out the awards in the dimly lit room, joking with parents in the audience.