The spray-painted messages included racial slurs and stated that both the president and Gov. Brown will "die soon," the Los Angeles Times reported Tuesday.
Santa Ana Police Cmdr. Tammy Franks said the U.S. Secret Service has been notified about the threats as well as the California Highway Patrol that is in charge of protecting Gov. Brown.
Last month, death threats against Brown as well as swastikas and other racist messages were found on buildings and churches in Santa Ana, Anaheim, Brea and Irvine, Calif.
Santa Ana is part of the greater Los Angeles metro area.
It is the seat of Orange County.