The FBI executed a search warrant Monday at Donald Trump's Mar-a-Lago resort in Palm Beach, Florida, as part of an investigation into the handling of presidential documents, including classified documents, that may have been brought there, three people familiar with the situation told CNN.

The former President confirmed that FBI agents were at Mar-a-Lago and said "they even broke into my safe." He was at Trump Tower in New York when the search warrant was executed in Florida, a person familiar told CNN.

"My beautiful home, Mar-A-Lago in Palm Beach, Florida, is currently under siege, raided, and occupied by a large group of FBI agents," Trump said in a statement Monday evening.

The extraordinary move to search the home of a former president raises the stakes for the Justice Department and comes as Trump's legal problems continue on multiple fronts. Trump is also expected in the coming months to announce he will launch another bid for the White House in 2024.

The Justice Department has two known active investigations connected to the former President, one on the effort to overturn the 2020 presidential election and January 6, 2021, and the other involving the handling of classified documents.

The search began early Monday morning and law enforcement personnel appeared to be focused on the area of the club where Trump's offices and personal quarters are, according to a person familiar with the matter.

The FBI's search included examining where documents were kept, according to another person familiar with the investigation, and boxes of items were taken. Following the National Archives' recovering of White House records from Mar-a-Lago in recent months, the FBI on Monday had to verify that nothing was left behind.

Trump's son, Eric, told Fox host Sean Hannity that "the purpose of the raid, from what they said, was because the National Archives wanted to, you know, corroborate whether or not Donald Trump had any documents in his possession."

Christina Bobb, Trump's attorney, said the FBI seized documents. "President Trump and his legal team have been cooperative with FBI and DOJ officials every step of the way. The FBI did conduct an unannounced raid and seized paper," Bobb said

There was communication between the FBI and US Secret Service before the search warrant was executed Monday, a person familiar with the matter said, allowing for the FBI to access the estate without any complications. There is only a small Secret Service footprint at Mar-a-Lago when Trump is not there.

CNN has reached out to the FBI for comment. The Justice Department declined to comment to CNN.

A White House official said it was not notified about the search. President Joe Biden, a senior administration official said, was unaware of the search of Mar-a-Lago until after it was reported on the news.

Investigation into documents

The National Archives, charged with collecting and sorting presidential material, has previously said at least 15 boxes of White House records were recovered from Trump's Mar-a-Lago resort -- including some that were classified.

In early June, a handful of investigators made a rare visit to the property seeking more information about potentially classified material from Trump's time in the White House that had been taken to Florida. The four investigators, including Jay Bratt, the chief of the counterintelligence and export control section at the Justice Department, sat down with two of Trump's attorneys, Bobb and Evan Corcoran, according to a source present for the meeting.

At the beginning of the meeting, Trump stopped by and greeted the investigators near a dining room. After he left, without answering any questions, the investigators asked the attorneys if they could see where Trump was storing the documents. The attorneys took the investigators to the basement room where the boxes of materials were being stored, and the investigators looked around the room before eventually leaving, according to the source.

A second source said that Trump came in to say hi and made small talk but left while the attorneys spoke with investigators. The source said some of the documents shown to investigators had top secret markings.

Five days later, on June 8, Trump's attorneys received a letter from investigators asking them to further secure the room where the documents were stored. Aides subsequently added a padlock to the room.

In April and May, aides to Trump at Mar-a-Lago were interviewed by the FBI as part of the probe into the handling of presidential records, according to a source familiar with the matter.

“It is a federal crime to remove classified documents wrongly. And so if you are filling out that affidavit and you have to list the crime, you can list that as the crime,” said Elie Honig, a former federal and state prosecutor and a CNN senior legal analyst.

Honig told CNN's Erin Burnett on “OutFront” that the timing of the search held with the longstanding department rule not to execute politically sensitive moves within 90 days of an election.

“Today is just about 90 days out exactly from the mid-terms; I think maybe 91 or 92 days out. That policy, that may be a reason why they did it today because they want to stay clear of that if they're interpreting that as a 90 day rule,” he said.

Members of GOP back Trump

Republican National Committee Chairwoman Ronna McDaniel claimed in a statement that Democrats “continually weaponize the bureaucracy against Republicans,” and a number of Republican lawmakers came to the former President's defense on social media.

House Minority Leader Kevin McCarthy, a California Republican, wrote that he had “seen enough.”

“Attorney General (Merrick) Garland: preserve your documents and clear your calendar. I've seen enough. The Department of Justice has reached an intolerable state of weaponized politicization,” the Republican leader wrote. “When Republicans take back the House, we will conduct immediate oversight of this department, follow the facts, and leave no stone unturned.”

GOP Sen. Rick Scott of Florida said that “we need answers NOW. The FBI must explain what they were doing today & why.”

But the chair of the House Oversight Committee, which is investigating Trump's handling of documents, called on the Justice Department to “fully investigate” the former President's handling of information.

“Presidents have a solemn duty to protect America's national security, and allegations that former President Trump put our security at risk by mishandling classified information warrant the utmost scrutiny,” Democratic Rep. Carolyn Maloney of New York said.

“Although details of today's actions at Mar-a-Lago are still emerging, it is clear that the Department of Justice must fully investigate President Trump's potentially grave mishandling of classified information.”

This story has been updated with additional details. (CNN)

*CNN's Dana Bash, Zachary Cohen, Jeremy Diamond, Shawna Mizelle and Megan Trimble contributed to this report.

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