Brown told reporters that at least 13 people were killed in the heavy storm and mudslides.
Flooding and mudslides also blocked roads in parts of Los Angeles County, shutting down major routes. Rain fell at more than 1.5 inches per hour, according to CNN, causing a series of horrific mudslides that uprooted trees, washed cars right off the road, and left homes utterly destroyed.
Mike Eliason, a spokesman with the Santa Barbara County Fire Department, said "multiple" rescue operations are underway in Montecito, which lies just east of Santa Barbara along the popular north-south 101 freeway.
Family of five rescued from debris of home following California mudslides
Emergency services said a number of people were unaccounted for and they expected the number of deaths to rise.
He said it's likely they'll find more people amid that destruction.
The debris and mud flows were first reported along with a house fire before 4 a.m. on the 800 block of Park Hill Avenue, according to Ventura CHP.
Santa Barbara County initially ordered 7,000 residents to evacuate and urged 23,000 to do so voluntarily, but only 10 to 15 percent complied, County spokeswoman Amber Anderson said Wednesday.
Flooding and debris flows closed United States 101 in the Thomas Fire burn area, located north of Ventura and south of Santa Barbara, according to California Department of Transportation. (Kenneth Song/Santa Barbara News-Press via Reuters) A search dog looks for victims in damaged homes after a mudslide in Montecito, Calif. on Jan 9.
The upmarket neighbourhood includes homes owned by celebrities like actor Rob Lowe and chat show host Ellen DeGeneres. Another 20,00 residents received voluntary evacuation warnings.More news: Oprah for president? Golden Globes speech stirs speculation of 2020 run