Giant markings of the numbers 8647 appeared Thursday on the National Mall in Washington, prompting an investigation by federal authorities and claims of “political violence” by the White House.

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An Interior Department spokesperson called the incident “deranged” vandalism that “will not be tolerated.”

“Any threat against the President is taken very seriously by the Department, and our U.S. Park Police will investigate this incident and hold those responsible accountable,” the spokesperson said.

U.S. Park Police told NBC News in a statement that they responded Thursday morning and that a probe is underway.

“The cause of the discoloration has not yet been determined,” the office said. “Grass samples have been collected for testing. The investigation is ongoing.”

The sequence of numbers is at the heart of a criminal case against former FBI Director James Comey, who was indicted in April after the Justice Department argued he had threatened President Donald Trump’s life by posting a photo on Instagram of seashells arranged to display “8647.” Trump is the 45th and 47th president.

Restaurant veterans have said “86” is “everyday lingo” for an item that has run out and should be removed from the menu.

“Anyone who engages in or endorses political violence or assassination culture must be condemned in the harshest terms possible. They should also immediately seek psychiatric help to treat their severe and debilitating case of Trump Derangement Syndrome that has warped their brains and made them sick in the head,” White House spokesperson Davis Ingle said in a statement Thursday.

A spokesperson for the U.S. Attorney’s Office for the District of Columbia — which would have jurisdiction over any potential case stemming from the incident — declined to comment.

A federal judge said in a separate case this month that “8647” by itself is not a threat, ruling that a protest flag with those numbers flying outside a federal courthouse in Washington on land managed by the National Park Service did not need to be taken down since the phrase constituted free speech.

The incident on the National Mall comes days ahead of the United Fighting Championship fights scheduled on the nearby White House grounds Sunday and celebration events scheduled to take place on the Mall this summer in honor of the U.S.’ 250th anniversary.