The blaze, reported about 1:30 a.m. at 1986 18th Ave., also killed 1-year-old Chloe Tse and her 33-year-old father, Raymond Tse.
Kin Fat Tse was Chloe’s grandfather, fire officials said.
Firefighters initially found Raymond Tse downstairs in full cardiac arrest. Crews then went upstairs and found the infant in a bathroom, fire Lt. Mindy Talmadge said.
Both were taken to a hospital, where they died. The grandfather also died at the hospital.
The child’s mother was treated for moderate smoke inhalation, Talmadge said.
The fire was extinguished at 2:01 a.m. Talmadge said the exact cause has not been determined, but an electrical problem or smoking materials may have sparked the blaze.
The fire caused an estimated $225,000 in damage to the home and $75,000 in damage to its contents, she said.