The City of Ottawa says it intentionally kept residents in the dark about a surprise late-night fireworks show because officials feared publicizing it would create a public safety risk.

Unused Canada Day fireworks fired over LeBreton Flats

The roughly 12-minute display lit up the sky over LeBreton Flats at about 10:53 p.m. Thursday, July 9, during the opening night of Ottawa Bluesfest. The fireworks had originally been slated for Canada Day but were scrapped because of severe weather.

Video of the unannounced show spread quickly on social media, with many Ottawa residents asking why no one had been warned about the late-night pyrotechnics.

In a statement to Global News, the city said the choice not to advertise the event was made by its Special Event Advisory Team, a group that includes representatives from the Ottawa Police Service, emergency services, Ottawa Public Health and other city departments.

Officials worried that announcing the rescheduled fireworks would pull large crowds onto streets around Bluesfest, which can already draw tens of thousands of people on its own.

This had the potential to create an "event surrounding an event."

Ryan Perrault, the city's general manager of emergency and protective services, offered that assessment in the statement, adding that the decision "followed careful consideration of public safety implications."

Already-primed fireworks posed their own risk

The Department of Canadian Heritage, which organizes the Canada Day fireworks, echoed the city's concerns. It said the unused fireworks had already been primed, and disarming them would have posed a significant risk to the fireworks crew.

"PCH, in collaboration with public safety and event partners, made an arrangement with Ottawa Bluesfest for the festival to use the fireworks and host a display at the end of their opening night," the department said in a statement.

City officials said promoting Thursday's display would have led large numbers of people to gather outside the ticketed Bluesfest grounds hoping to catch a glimpse of the show.

After weighing the options, the Special Event Advisory Team "determined that the public safety risks associated with encouraging additional attendance in the surrounding area outweighed the benefits of broader notification," the city said.

The city acknowledged the surprise disturbed some residents.

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

Perrault said bylaw and regulatory services had received 38 fireworks-related complaints as of Friday morning.

He added that staff will review the public feedback as part of a post-event debrief to determine whether changes are needed for future events.