With the Atlanta attack and the Bowling Green massacre still fresh in their minds, social media users are once again "mourning" a fake incident referenced by the Trump White House, this time in Sweden.

U.S. President Donald Trump himself started the fake news story at a rally on Saturday, when he implied that there had been a major security incident in Sweden the night before. Trump was criticizing refugee immigration in Europe, and linking it to countries hit by terror attacks. First he mentioned Germany, where there have been multiple terror-related incidents in recent months. Then he referred to what sounded like a specific incident in Sweden.

"Look at what's happening last night in Sweden," Trump told supporters in Florida.

Swedes immediately mocked Trump for his remark, as there were no major security incidents in Sweden on Friday.

"Sweden? Terror attack?" tweeted Carl Bildt, Sweden's former foreign minister. "What is he smoking? Questions abound."

Trump later tweeted that he was referring to a Fox News story on immigration that he saw on TV the night before the rally.

Nevertheless, Trump clearly made specific reference to an incident that happened "last night in Sweden."

Twitter quickly jumped on Trump's confusing comment, with social media users tweeting their insincere condolences for the people of Sweden.

The incident also triggered memories of two other phantom terror attacks that have been referenced by White House staff in the past.

In late January, White House Press Secretary Sean Spicer made three references to an attack in Atlanta, in televised interviews and in a press briefing. Spicer later told ABC News in an email that he "clearly meant Orlando."

Trump counsellor Kellyanne Conway also appeared to make up a terror attack days later, when she referred to a supposed "Bowling Green massacre" during an interview with MSNBC's Chris Matthews. "Most people don't know that because it didn't get covered," she said.

Conway later walked back her comment, saying she had been referring to an incident involving two Iraqi nationals living in Bowling Green. 

Social media users were quick to lump all three fake terror attacks together, with insincere tributes to the dozens, even hundreds of fake victims involved.

Trump appears to have been referring to a Friday segment on Fox News' "Tucker Carlson Tonight," in which a documentary filmmaker spoke about a rise in violent crime in Sweden.

Triggered by the backlash, Trump supporters rushed to his defence. Many shared links to incidents of alleged violence involving immigrants in Sweden.

But while those stories circulated among pro-Trump circles, no one could come up with a major security incident from Friday, Feb. 17, 2017.

Trump suggested in a tweet on Monday that he was criticizing immigration. "The FAKE NEWS media is trying to say that large scale immigration in Sweden is working out just beautifully. NOT!"

But the question remains: If he was talking about immigration, what was he referring to "last night in Sweden"? Or was he referring to something he saw last night on TV?