Upwards of 80 agents raided the Million Air terminal Wednesday morning. Joined by a number of other agencies, the investigation was led by the FBI.
"We're seeking allegations of criminal activity, but again, this is a continuing investigation. At this time, we're not at liberty to provide details," said Laura Eimiller of the FBI.
The FBI also served a search warrant at the Riverside home of Scot Spencer, who manages the Million Air terminal.
It was just over three months ago that a grand jury came down with a report extremely critical of Spencer's activities at the airport.
The report even referenced an order from the Department of Transportation that Spencer should be "banned from the aviation industry."
The grand jury report said Spencer is a convicted felon, who before working at this airport, served prison time for bankruptcy fraud.
The FBI was at the airport collecting evidence, but they did not say who is at the center of the investigation.
"Because of the fact that a judge has sealed the affidavits in support of the search warrants, we are prohibited completely from commenting on any details about the investigation," said Eimiller.
No one has been charged or arrested in connection to the investigation.
Josie Gonzales, chair of the San Bernardino County Board of Supervisors, said she is giving a 24-hour notice of an emergency meeting with the board to discuss what's happening with the airport and how to move forward.
"There is no reason why things should not be brought out before the public, discussed and fixed. If there is something wrong, we can fix it," said Gonzales.