Police officers responded to a report of a woman being stabbed at 4:20 p.m. at a residence on the 13900 block of Herron Street.
When they arrived, they found a man covered in blood and a woman lying on the living room floor with multiple stab wounds.
The woman, 55-year-old Matilda Sanchez, was pronounced dead at the scene.
An uncle who lives in the residence said the 22-year-old son of Sanchez stabbed her. The son was arrested.
A large bloody butcher knife was found near the woman's body.
Police said officers had responded to the residence recently for reports of the son setting fires.
Anyone with information is urged to call LAPD's Mission Homicide Unit, at (818) 838-9954. Anonymous tips can be called into Crime Stoppers at (800) 222-TIPS, or by texting 274637 (C-R-I-M-E-S on most keypads) with a cellphone. All text messages should begin with the letters "LAPD." Online tips may be placed at LAPDOnline.org, click on "webtips" and follow the prompts.