The blaze broke out shortly before 11 p.m. Sunday on the 1700 block of Piermont Drive. Fire officials say the fire started in the living room and spread quickly. Authorities said the fire doesn't appear to be suspicious in nature.
Authorities said the woman died at the scene and her 3-year-old son died at a nearby hospital.
The woman's husband and 8-year-old daughter were also hospitalized, but their conditions were not known. One firefighter was hospitalized for smoke inhalation.
The identities of the victims were not immediately released.
The female victim's father, Willie Gonzales, believes that candles may have been to blame for the fire. Others are pointing the finger at smoke detectors.
"The issue of smoke detectors is a huge one, and unfortunately it does not appear that smoke detectors, if they were here, were functioning, and they would have perhaps provided this family an opportunity to get out of the house. This is a very tragic event," said Los Angeles County Fire Department Battalion Chief Joel Harrison.
Gonzales said he doesn't believe his daughter's home was equipped with a working smoke dectector.
"I wish it would have been me instead of them," said Gonzales. "My daughter was so good with everybody. Everybody loved her."
The cause of the fire was under investigation.