After the FBI executed a search warrant on Donald Trump's residence at Mar-a-Lago on Monday, supporters of the former president gathered outside.

Sources told ABC News that the warrant was related to 15 boxes of potentially classified documents that Trump took with him from the White House to Mar-a-Lago.

The former president called the legal search "prosecutorial" on social media.

"This has never happened to a President of the United States before," Trump said. The raid on my home was not necessary after I worked and cooperated with the Government agencies.

—Royal Intel 👑 (@RoyalIntel_) August 9, 2022

The followers of the ex-president held signs and shouted obscenities as they protested the search.

In front of FBI office locations in Palm Beach, Phoenix, Arizona, and Washington, DC, supporters were summoned by alt-right organizers.

—HeadlineHunter! 🚨 Alerts (@headlinehunter_) August 9, 2022

There were calls for revenge against the FBI in posts from supporters of the gatherings. The federal investigators were called a terrorist organization by some users, while others asked the former president to announce a revolution.

The National Archives and Records Administration did not respond to Insider's request for comment.