Deputies with the Los Angeles County Sheriff's Department responded to a business parking lot late Thursday night in the 4800 block of Civic Center Way.
The child, who's been identified as Mia Gonzalez, was found unresponsive inside a vehicle. She was transported to a local hospital where she was later pronounced dead.
Her mother, 38-year-old Maria Avalos, was also found in the vehicle, according to authorities. She was detained at the scene and later booked on suspicion of murder.
According to the Los Angeles County autopsy report released Saturday, the child's death has been ruled a homicide.
The cause of death was reported as "combined effects of strangulation and sharp force," according to the autopsy report.
A GoFundMe page has been set up for the family.
The case will be presented to the Los Angeles County District Attorney's Office for review on Tuesday, Jan. 30.
Anyone with information about this incident is urged to contact LASD's Homicide Bureau at 323-890-5500.