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Fireworks explode over the Ottawa River during last year's Canada Day festivities.Spencer Colby/The Canadian Press

In a bid to get rid of potentially dangerous Canada Day fireworks left unused because of bad weather, municipal and federal officials set off a surprise late-night show in Ottawa this week that astonished residents.

One moment, it was a quiet Thursday night, then, out of the blue, a major fireworks display was unleashed around 11 p.m. over the core of the country’s capital.

“It really was insane. That’s all I can say,” Ariel Troster, the city councillor for Somerset Ward in the city’s downtown, said in an interview on Friday.

“Of course, I am getting bombarded by e-mails. What I am telling people is, ‘It woke me up too. Nobody told me either. It’s unacceptable.’”

As of Friday morning, the city’s bylaw department had received 38 complaints related to the unexpected show, according to a statement from Ryan Perrault, general manager of emergency and protective services.

Later in the day, the Canadian Heritage department laid out a scenario that was largely unknown to residents of the city ahead of the explosive overnight show.

Extreme weather on Canada Day forced the cancellation of a planned fireworks display at LeBreton Flats, near Parliament Hill. Because the fireworks were already primed, it would have posed a safety risk to the fireworks crew to try and disarm them, said a statement issued by Heritage spokesperson Caroline Czajkowski.

In addition, there was a concern that advertising the use of the fireworks would have created a challenging situation if crowds turned up for the display because the Ottawa Bluesfest show was under way, bringing crowds into the area of the city where the fireworks were located.

According to Ms. Czajkowski’s statement, there was an interest in ensuring that crowds did not exceed the safe capacity of the LeBreton Flats Park and surrounding area.

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Mr. Perrault’s statement said there were worries about “an event surrounding an event,” causing a safety risk and placing additional pressure on the crowd.

So, the city’s event advisory team, whose members include representatives of the Ottawa police, emergency services and Canadian Heritage, decided to proceed with the show.

“The public-safety risks associated with encouraging additional attendance in the surrounding area outweighed the benefits of broader notification,” said Mr. Perrault’s statement.

“Staff recognize that the display caused concern and disturbance for some residents, particularly given the absence of advance notice.”

NAV CANADA, which manages Canadian civil airspace, was in on the planned display.

As a result, the non-profit corporation published a notice three days before the event, restricting airspace up to 2,000 feet above sea level during the show, according to media relations manager Gabriel Bourget.

Mr. Bourget said in a statement that the restriction applied to all aircraft, including drone, and except for police and medevac operations.

He noted that the order was intended for pilots and aircraft operators.

“Public notification of fireworks displays is the responsibility of event organizers and local authorities,” said the statement.

Ms. Troster, one of two central Ottawa city councillors, said the unexpected fireworks may have been distressing to survivors of warfare elsewhere in the world who now live in Ottawa.

“I wasn’t pleased about it – not because I don’t like fireworks but because no one was informed about it, including me.”

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