TORONTO — An explosion at a Toronto power facility knocked out power in Canada's largest metropolis, and briefly disrupted a state dinner for Queen Elizabeth II.
Hydro One, the power company for Canada's most populous province of Ontario, said the blackout hit at 4:42 pm local time (2042 GMT), affecting the city's subway, several commuter trains and traffic lights at the height of the evening rush hour.
Up to 250,000 people in the city center were also without electricity -- an estimated 900 megawatts in total lost from the grid -- amid an extreme heat alert, Daniele Gauvin, spokeswoman for provincial utility, told AFP.
Temperatures in the city reached 34 degrees Celsius (93 Fahrenheit).
Public broadcaster CBC said firefighters were kept busy rescuing people trapped in elevators while policemen directed traffic.
The queen, at the end of a nine-day trip to Canada with her husband, Prince Philip, was to attend a state dinner hosted by Prime Minister Stephen Harper at the Royal York Hotel in downtown Toronto, but the hotel was without power leading up to the event.
The dinner was delayed by one hour, but went on.
"People were getting ready to go home when the power went out," businessman Falik Raja, 40, told AFP. "There was some panic because many people were working in high-rise buildings... and the lifts stopped working."
"People were hurrying down staircases to the ground floor and then headed out to their cars" or to the train station, he said, but there were no traffic lights and so tens of thousands of motorists got stuck in traffic jams.
Thousands of people also packed into Union Station to wait for subway cars and commuter trains to trickle back into service after power was restored. "Gradually the crowds started departing," said Raja.
Gauvin said the outage was caused by a fire at a transformer station in the heart of Toronto, but that the blaze was extinguished shortly afterwards. An inquiry is to be conducted into the cause of the fire, she said.
As she spoke, power started coming back on in parts of Toronto. By 8:30 pm (0030 GMT Tuesday) it was restored to the entire city.
No injuries were reported.
Torontonians last experienced a major blackout in 2003, on a similarly seasonally hot day in mid-August.
That massive power outage affected 55 million people in Ontario plus much of the northeastern and midwestern United States, in the worst widespread power failure in North America.
In the Ontario region, telephone networks remained mostly operational but were overloaded, water systems lost pressure in several cities, and the Toronto stock exchange was closed.
It lasted several days before power was fully restored.