President Donald Trump on Monday said vandals used chemicals to write "a gigantic 86 47" on the grass field around the Reflecting Pool in Washington, D.C.

The president's latest comments came as federal authorities continued investigating alleged vandalism at the recently renovated Reflecting Pool on the National Mall, a centerpiece of Washington's preparation for America's 250th anniversary celebration.

In a Truth Social post Monday, Trump said, "Of the MANY Statues and Fountains that we rebuilt, renovated, cleaned, and fixed, the only one that was Vandalized was the Reflecting Pool, which is being taken care of, ASAP!

"It has been given a 300 foot long gash, chemicals have been illegally placed in the water, and the beautiful new grass field has been destroyed with a gigantic 86 47 chemically carved into it (Probably inspired by Dirty Cop, James Comey!)."

Comey, the former FBI director, faced criticism from conservatives after posting a photo of seashells arranged in the numbers "86 47," which stands for eliminate Trump.

Comey denied any violent intent.

Trump also warned of a long prison sentence for the vandals.

"Please remember that there is a 10 year prison sentence for the destruction, or even the attempted destruction, of such things — Which will be fully enforced! Thank you for your attention to this matter," Trump wrote.

Trump has repeatedly defended the $14.7 million renovation project, which included draining and refurbishing the historic pool.

"The Reflecting Pool was never so beautiful as it was just one week ago," Trump wrote Saturday. "We are very proud of what we have done with this magnificent structure."

Federal prosecutors are taking the allegations seriously.

U.S. Attorney Jeanine Pirro said Sunday that multiple arrests have been made and promised that those responsible would face prosecution.

"Anyone who is in a position of vandalizing or attempting to vandalize will face the criminal justice system in D.C.," Pirro said during a TV appearance.

Trump also announced over the weekend that the U.S. Park Police had arrested multiple individuals connected to the vandalism investigation.

He called the acts "a true affront" to former Presidents George Washington and Abraham Lincoln.

The renovation project has faced scrutiny in recent weeks after reports of peeling blue paint and algae blooms in the pool.

Critics have questioned the quality of the work, while Trump has blamed the problems on vandalism and sabotage.

According to AFP, workers have been draining portions of the pool and using hydrogen peroxide treatment to combat algae growth while repairs continue.

After personally inspecting the site Sunday, Trump vowed that repairs would begin immediately.

"WOW, who would do such a thing?" the president wrote. "SICK, DERANGED PEOPLE! We will fix it."