Olivia Carolee Culbreath is accused of causing the roughly 4:45 a.m. Sunday crash in Diamond Bar. She remains hospitalized, and it's unclear when she will appear in court.
Culbreath, who has a previous drunken driving conviction, is being held in lieu of $6 million bail.
She was headed east in westbound lanes at speeds up to about 100 mph in a new Chevrolet Camaro when she crashed head-on into a 1998 Ford Explorer, and a 2006 Ford Freestyle also struck the Explorer, according to the CHP.
The dead in the Camaro were 24-year-old Maya Culbreath, Olivia's sister, and Kristin Young, 21, of Chino, according to the Los Angeles County Coroner's Office. Four people ejected from the Explorer died. They were identified as Huntington Park residents Gregorio Mejia-Martinez, 47; Leticia Ibarra, 42; Jessica Mejia, 20; and Esther Delgado, 80.
Olivia Culbreath was convicted of driving under the influence on April 13, 2010, according to Department of Motor Vehicles records. She was stopped for two more violations before her license was reinstated in December 2011, according to the DMV, which lifted restrictions on her license last week.—City News Service contributed to this report.