The death toll in the flooding and landslide that last week hit Montecito, California - northwest of Los Angeles - rose to 20 on Sunday, with four people remaining missing, authorities said.

Santa Barbara County authorities reported the finding of another body on Saturday afternoon, saying that they will continue with their search for the missing after the devastation brought by a sudden heavy rainstorm last Tuesday.

The area, which had been severely affected by the largest forest fire in modern California history, experienced a mudslide after a downpour on Tuesday that left 28 people injured, some of them seriously, according to the Santa Barbara County Fire Department.

County officials also said that the flooding and landslide had destroyed about 100 homes and damaged another 500.

Authorities blame the mudslide on the Thomas Fire, the largest in recent California history, which in December burned some 114,000 hectares (about 285,000 acres), thus removing the terrain's covering vegetation.

SBCFD spokesman Tom Henzgen said that efforts are focusing on locating four missing people, including Fabiola Benitez Calderon, 28. The woman's children - Jonathan Benitez, 10, and Kailly Benitez, 3 - are among the dead.

The affected area is one of California's tourist attractions where homes range in value from $1.4 million to $4 million and where a number of famous TV personalities live, including Ellen DeGeneres and Oprah Winfrey, along with actor Rob Lowe.

The local residents will be without potable water and electricity service for a "long time," according to the Santa Barbara County Emergency Management Office.

Authorities also said that the heavily-traveled Interstate 101 will remain closed for an "indefinite" period, although it had been expected to be reopened on Monday.

Each day, some 100,000 vehicles use the roadway.