"The FBI is investigating allegations of criminal acts surrounding the incident at Scottsdale Fashion Square in May, 2020," the bureau said in a statement to sister station KABC. A search warrant was also executed in Las Vegas but no arrests were immediately planned. No other details were disclosed.
KABC's chopper was over the scene as multiple firearms that were scattered across the Calabasas property, including a long gun propped up against a hot tub in the backyard, were being seized by authorities.
In early June, misdemeanor charges were filed against Paul following a riot at the mall outside Phoenix. Paul said he was merely trying to find people protesting against the death of George Floyd.
The Scottsdale Police Department said Paul was identified as a participant in the riot at the location and was charged with criminal trespass and unlawful assembly.
Paul denied looting and said he wanted to "share our experience and bring more attention to the anger felt in every neighborhood we traveled through."
"It has been decided that in the cases charging Jake Paul, Arman Izadi and Andrew Leon, it is in the best interest of the community to dismiss misdemeanor charges without prejudice so that a federal criminal investigation can be completed," Scottsdale police said in a Wednesday news release, referring to Paul and two others who were charged in the case.
RELATED: Jake Paul's house party in Calabasas draws backlash from mayor
Wednesday's search comes about two weeks after Paul hosted a raucous party at the mansion, sparking backlash due to the lack of masks and social distancing among the dozens of guests.
Calabasas Mayor Alicia Weintraub expressed outrage over the large party, which took place despite rising coronavirus cases, hospitalizations and deaths in California.
Videos of the house party went viral on social media, where Paul himself has some 20 million followers.
Weintraub said she learned of the party when residents complained, telling her they saw "tons of people walking on the street unmasked and then gathering."
"I was very upset that somebody would hold such an outrageous gathering in our community," the mayor told ABC News, noting that the city had recently enacted a policy of issuing a minimum-$100 fine for not wearing a facial covering in public. "We're trying to do everything we can to get our numbers down and keep our community safe, and something like this just does the opposite."
The Associated Press contributed to this report.