The crash also killed Walker's friend and financial adviser Roger Rodas, according to Walker's publicist, Ame Van Iden. She said Walker was a passenger in the car when the two drove away in a 2005 red Porsche Carrera GT from a fundraiser in the community of Valencia, about 30 miles northwest of downtown Los Angeles.
Sheriff's deputies found the car engulfed in flames when they arrived at the site of the crash, near the fundraiser at Rodas' sport car dealership. Officials have not identified either person found in the car.
On Sunday, fans of Walker, 40, gathered to leave flowers, candles and memorabilia from the action movies.
Walker is "gone but he'll never be forgotten because there are so many people that look up to him," Joel Perez, 23, told the Los Angeles Times at the memorial.
Sheriff's deputy Peter Gomez said investigators are working to determine how fast the car was traveling and what caused it to go out of control, including whether the driver was distracted or something in the road prompted him to swerve.