But more than three days after the shooting, the response from Canada's southern neighbor has been remarkably muted.
President Donald Trump did call Trudeau on Monday to offer his condolences. While the White House did not offer a statement about the exchange, a spokesman for Trudeau told Canadian reporters that Trump had also "offered to provide any assistance as planned" during the phone call. White House spokesman Sean Spicer later confirmed the call took place when asked at a news briefing on Monday.
On Trump's famed social media accounts, a bullhorn the president often uses to communicate with millions of followers, the attack in Quebec City does not appear to have been mentioned at all.
Trump's personal Twitter account has posted 16 times since the shooting, and the official POTUS account on the same service tweeted or retweeted other messages 30 times. Neither mentioned the Quebec City attack as of Wednesday afternoon. During the same period, a Facebook account linked to Trump posted at least 20 times. It also had not mentioned the shooting by Wednesday.
That radio silence is unusual for Trump. The president is a ravenous consumer of media, and even before he entered the White House he was known to respond quickly and forcefully to acts of terror and mass murder abroad.
Just a few hours after an attack in Berlin on Dec. 19 in which a Tunisian-born man drove a truck through a Christmas market, killing 12 people, Trump released a statement that suggested "innocent civilians were murdered in the streets" as they prepared to celebrate the holiday. Trump fired up a tweet in just a few hours, noting that there had been a number of violent acts on the same day.
"It is only getting worse," the soon-to-be president said. "The civilized world must change thinking!"
A few days later he returned to the subject of the Berlin attack. "Such hatred!" he wrote. "When will the U.S., and all countries, fight back?"
Over the past year, Trump tweeted more than 4,000 times. At least 49 of those tweets directly mentioned "terror" in some way. He often quickly and clearly responded to terror attacks on foreign soil. Here are just a few examples:
In almost every case, Trump was responding to an attack claimed by a militant Islamist group. One of the only exceptions is the shooting in Munich, Germany, last July that left 10 people dead, including the perpetrator. While there was initial speculation that the attack was carried out by an Islamic extremist, it was later announced that the attacker was not religiously motivated and had in fact been obsessed with school shootings.
Trump did also refer, in passing, to a shooting at a mosque in Switzerland that left three injured in his Dec. 19 tweet. However, police later said that incident was not terror-related.
The attack in Quebec City does not appear to have been carried out by a Muslim or inspired by Islamic extremist ideology. In this case, the victims were Muslims and the shooting took place at a mosque, apparently the first mass shooting at an Islamic house of worship in North America.
The suspect, Quebec native Bissonnette, was attracted to far-right politics and known for posting comments on social media that denigrated refugees and women on social media, an acquaintance told the Globe and Mail. Bissonnette was also said to be a supporter of French National Front leader Marine Le Pen — and President Trump himself.
Trump also appears to have never mentioned the 2015 Charleston church shooting on his Twitter account, and did not share a reaction when white supremacist Dylann Roof was found guilty of the murders of nine African American churchgoers in the attack.
The president has only been office for less than two weeks, and he may be finding that the transition period keeps him busier than he was last year. But since Sunday's attack, Trump has found time to tweet a number of times about an executive order that blocked access to the United States for Syrian refugees and a number of other Muslim-majority countries.
Meanwhile, members of Trump's camp have seemingly referred to the shooting in Quebec City as a justification for Trump's executive order. Spicer told reporters Monday that the attack was a "terrible reminder" of "why the president is taking steps to be proactive instead of reactive when it comes to our nation’s safety and security.” Donald Trump Jr., the president's son, was also found to have "liked" a tweet that suggested that if the Quebec City shooter was found to be a Muslim, it would give Trump's executive order "political capital."
The White House did not respond to a request for comment from The Washington Post.