More than 200 agents from around the country participated in the raids across the Hemet San Jacinto Valley.
Search warrants related to the attacks were served at more than 35 locations. Twenty-three people were arrested, some for parole violations.
"Certainly that is our priority, number one, to identify and take into custody those responsible, with the ultimate goal of stopping the incidents and stopping the attacks on the city and on the police department," said Brown. "So we're certainly optimistic that we're one step closer to that today."
Brown said a variety of arrests were made, including for weapons violations.
Riverside County District Attorney Rod Pacheco said all of those arrested were white supremacists.
Hemet Police have been targeted with booby traps at least three times since New Year's Eve, including by a ballistic device that was strapped to a fence at the gang unit's compound and sent a bullet within inches of an officer's face.
The Associated Press contributed to this report.