Donald Trump has accused unnamed Hillary Clinton allies of being the arsonists behind the firebombing of a Republican headquarters in North Carolina on Saturday.

Taking to Twitter Sunday afternoon, Trump alleged that “animals” representing Clinton and Democrats in North Carolina had helped destroy the Republican Party’s offices in Hillsborough, North Carolina.

Animals representing Hillary Clinton and Dems in North Carolina just firebombed our office in Orange County because we are winning @NCGOP — Donald J. Trump (@realDonaldTrump) October 16, 2016

Local law enforcement is investigating after somebody threw a flammable bottle through the office’s windows on Saturday night, setting much of the furniture inside ablaze, according to the Charlotte News-Observer. In addition to the fire, someone spray-painted an adjacent building with the message, “Nazi Republicans get out of town or else.” Nobody was injured in the attack.

Trump didn’t provide any evidence for the claim that people representing Clinton were behind what Republican officials in North Carolina are calling “an act of political terrorism.” (Trump did say the attack occurred “because we are winning,” though most polls show Clinton leading in the state by several points.)

Authorities have said nothing to give any reason to suspect Clinton or North Carolina Democrats orchestrated the attack. Local law enforcement, Clinton, and Republicans in North Carolina have all responded by condemning the attack and calling for a full investigation.

The attack on the Orange County HQ @NCGOP office is horrific and unacceptable. Very grateful that everyone is safe. — Hillary Clinton (@HillaryClinton) October 16, 2016

Thank you for your thoughts & prayers, Sec. @HillaryClinton. — NCGOP (@NCGOP) October 16, 2016

This is the country of freedom & liberty- not of hate & violence. The orange co gop will rebuild and be renewed. #ncpol @NCGOP pic.twitter.com/fiYvFC5Mvx — Kami Mueller (@kamimueller) October 16, 2016

Why Trump’s comments should worry us

In isolation, Trump’s wild claims would be worrisome enough: Presidential candidates don’t normally make unfounded accusations that their opponents are using covert agents to carry out fire-bombings. (Knee-jerk accusations of violence also seem like a dangerous thing for a commander in chief to have a habit of doing.)

But there’s another critical context for understanding Trump’s tweet: The Republican presidential nominee has begun making increasingly conspiratorial claims that a cabal of “global elite”s is rigging the election for Clinton.

As part of that, he’s begun encouraging his fans to monitor polling stations in places like Philadelphia — a sign his supporters are interpreting to mean that they should racially profile polling stations. Just today, top Trump surrogate Rudy Giuliani was on cable TV claiming that the vote totals of the “inner cities” were prone to massive voter fraud. (They’re not.)

As Vox’s Dara Lind has written, this is extremely dangerous:

Trump has urged his followers to spend time on Election Day intimidating nonwhite voters. He tells them that after they vote on November 8, it’s their duty to go en masse to “some other place” and make sure that no one’s engaging in voter fraud … It’s one thing to have election monitors stationed at polling places to make sure poll workers and campaign volunteers aren’t breaking election law; it’s quite another to encourage groups of vigilantes to hang out at polling places in unfamiliar neighborhoods, with the stated goal of making people feel too uncomfortable to vote if they look like they shouldn’t be voting.

Baselessly accusing Clinton of being behind the firebombing is crass. But it’s also being used to fit a broader narrative that his political opponent is so dangerous, so crooked, that she’s willing to commit acts of terrorism to influence the voting results. And if that’s true, then of course she’s willing to steal an election by other means, and of course his supporters should doubt the results.

We still have 22 days left in maybe the most acrimonious political campaign in modern American history. And that is a lot of time for Trump to prime his most extreme followers to believe they’re up against not just someone willing to skirt email management rules, but a criminal willing to risk actual, real-world violence against American citizens.