Gwendolyn Taylor, 61, was enjoying an afternoon with her family when she was hit by a stray bullet.
The shooting happened Saturday afternoon at Rogers Park in Inglewood.
Taylor and her family, including several of her grandchildren, were picnicking when gunfire rang out.
Family members said the 61-year-old shielded one of her grandkids with her body.
She was struck once and died at a hospital.
A 15-year-old boy standing nearby was also hit by a stray bullet, but he was not seriously injured.
Investigators said that the suspect was walking through the parking lot of the park when he started shooting at a 16-year-old boy, who ducked behind a car.
The bullets then hit two innocent victims, including Taylor.
"This death, as untimely as it is, will not go unanswered. The city of Inglewood and its police department will leave no stone unturned in furtherance of looking for this suspect, finding him, identifying him and bringing him to justice," said Inglewood Police Chief Jacqueline Seabrooks.
Authorities said they have no leads and very little information to go on.
Anyone with information was urged to call the Inglewood Police Department at (888) 412-7463.