According to police, SWAT officers are at the house where the victims were found. The shooter is described as a 61-year-old Asian woman who was wearing a white shirt and gray sweatpants.
Police still are looking for the woman, a law enforcement source said.
Police said a total of six people have been shot. A law enforcement source says four are dead.
Reportedly, two families with a total of 11 people were living in the home, according to a woman at the scene. According to police, someone in the home called 911 and reported his grandmother was mentally ill and had opened fire.
Medics are working on wounded victims in the front yard, police said.
The shootings happened about 1:30 p.m. PDT. Additional shots were fired while medics were at the scene at 1:38 p.m., police said.