TORONTO — Four people were injured, some seriously, after a shooting at the city’s “We the North” NBA championship celebration for the Toronto Raptors, police said.

In a Monday evening news conference, Toronto Police Chief Mark Saunders said officers arrested three people and seized two firearms. It was unclear if any of the suspects were among the four injured. The victims suffered non-life threatening injuries, and Saunders could not say how many other people were hurt.

The violence punctuated a day when national pride swelled in Toronto, as the fourth largest city in North America rang in its team’s first NBA championship and the first won by an NBA team outside the United States.

“I’m not happy that there’s a shooting that occurred,” Saunders said. “But I’m also not going to let this shooting define the fantastic event that took place where we had so many people who had such a great time."

In a statement, the city’s mayor, John Tory, thanked police for their “quick response to today’s most unfortunate shooting after an otherwise spectacularly successful day.”

“It is disappointing and I’m sure a great source of anger for more than just me that anyone would carry a gun and discharge it at what was otherwise a joyous celebration,” he said. “I hope those found responsible will be held to account to the full extent that the law permits. I want to commend and thank the millions of other people

Earlier that afternoon, police said on Twitter that shots were fired at the celebration, and that two victims suffered injuries deemed “serious but not life threatening.” Officials said the shooting took place near Bay and Albert streets, which intersect east of Nathan Phillips Square, where a crowd of thousands had gathered.

What sounded like seven gunshots, fired several seconds apart, could be heard in the background as 680 NEWS reporter Mark Douglas was broadcasting live from the square during the rally. Douglas was in the middle of an ordinary update, speaking about the logistics of keeping the crowd hydrated on a sunny and warm day, when the bangs cut through the air.

As one of the Raptors owners was speaking on the stage, the rally’s emcee interrupted to alert the crowd. “I want to make sure everyone stays calm,'' the host, sportscaster Matt Devlin, said, according to the Associated Press. “This is serious. Everyone stay calm. . . . There is an emergency being dealt with.''

Speeches by players and others, including Canada Prime Minister Justin Trudeau, quickly resumed. Ontario Premier Doug Ford and Tory were among the national and local leaders onstage; Trudeau’s office confirmed to The Post that he was safely escorted from the scene but declined to comment further, citing a policy of not disclosing details of the prime minister’s security.

"I hope all those injured in today’s shooting have a speedy recovery, and I’d like to thank the Toronto police for acting so quickly,'' Trudeau tweeted. “We won’t let this act of violence take away from the spirit of today’s parade.''

The festivities began later than the scheduled 10 a.m. starts and wound through the streets of Toronto; Nathan Phillips Square was the final destination. A stage had been erected there, and Raptors players arrived at the stage after 2 p.m., later than expected because of the large crowds thronging and clogging the route, which appeared to have no barriers to hold fans back.

After the gunfire, as spectators scattered, dozens took refuge in Osgoode Hall, a courthouse near the square, where authorities briefly held them under lockdown. Parents hugged their young children, many of whom were distraught and crying.

Mary Hopple, who attended the parade, said Trudeau was speaking when she heard a sound that resembled fireworks.

“Then there was a mad stampede of people clearly in a lot of panic,” she said. “I didn’t know what to do so I just ran, too.”

Christian Blazekovic said he didn’t hear gunshots, but knew something was amiss when he saw the crowd scrambling.

“Everyone just started running, mass amounts of people just sprinting for their lives,” he said. “It was anarchy because it was already crowded and areas had been blocked off for the parade."

Mohammed Jabbar was selling Raptors apparel at a stall near the scene of the shooting and he said he heard “two loud bangs” followed by a swarm of people running.

Police cordoned off about a city block for investigation.

Toronto is a relatively safe city. But in 2018, it experienced a surge in gun violence, with the number of homicides caused by shootings up significantly. In late 2018, the Trudeau government pledged more than $7 million CDN, or roughly $5.2 million, to help combat gun crime there.

The violence has intensified a long-running debate about guns in Canada, as gun control advocates call on Ottawa to tighten rules on gun ownership and an increasingly vocal group of pro-gun groups use U.S.-style tactics to counter those calls.

The fact that Toronto’s victory celebration was marred by gunshots will no doubt deepen questions about how best to curb gun-related violence and put the issue back on the national agenda heading into a federal election in October 2019.

The city had not held a sports celebration of this size since the Blue Jays won their second consecutive World Series in 1993. During that parade and rally, fans climbed trees and statues lining the route to get a glimpse of the team. The Maple Leafs have won the Stanley Cup 13 times, but not since 1967.

Emily Rauhala contributed to this report.