Walker died Saturday afternoon, Ame Van Iden told The Associated Press.
A statement on the actor's Facebook page said he was a passenger in a friend's car, and that Walker was in the area to attend a charity event for his organization Reach Out Worldwide.
"We ... are stunned and saddened beyond belief by this news," the statement said.
The Los Angeles County Sheriff's Department said that deputies found a car engulfed in flames when they responded to a report of a collision in the community of Valencia. Two people who were found in the car were pronounced dead at the scene.
The Santa Clarita Signal reports a red Porsche crashed into a light pole and tree and burst into flames.
Bing: More about Paul Walker
Walker was working on "Fast & Furious 7" at the time of his death. He also starred in the suspense drama, "Hours," which is set for release this month.
Walker rode the "Fast & Furious" franchise to stardom, starring in all but one of the six action blockbusters, beginning with the first film in 2001. The blond-haired, blue-eyed Los Angeles-native brought California surfer good-looks and an easy, warm charm to the popular street-racing series.
"All of us at Universal are heartbroken," Universal Pictures said in a statement. "Paul was truly one of the most beloved and respected members of our studio family for 14 years, and this loss is devastating to us, to everyone involved with the 'Fast and Furious' films, and to countless fans."
The son of a fashion model and a sewer contractor, Walker grew up in a working class, Mormon Los Angeles household. The oldest of five siblings, Walker's mother began taking him to auditions as a toddler. He was a child model beginning at the age of 2.
Walker has said the early induction to show business wasn't to start him on a career path, but as a way to help provide for the family.
After a string of TV roles as a child in the '80s, Walker made his feature film debut in the 1998 comedy "Meet the Deedles." Supporting roles in the films "Pleasantville," ''Varsity Blues" and "She's All That" followed.
His performance in the 2000 thriller "The Skulls" caught the eye of producer Neal H. Moritz, who cast him in "The Fast and the Furious" as undercover police officer Brian O'Conner. Adapted from a Vibe magazine article about underground street races, the film became an unexpected hit.
In the sequel, "2 Fast 2 Furious," Walker moved to center stage with his co-star Vin Diesel momentarily dropping out. Walker, a self-described "gearhead," kept his character's sports car from the film.
Walker starred in other films, including the crime thriller "Running Scared," the Antarctic adventure "Eight Below" and the heist film "Takers." Though his stardom didn't make as much of an impact outside the "Fast & Furious" series, Walker continually drew praise from his co-stars and directors as a kind-hearted and eager collaborator.
And "Fast & Furious" proved unusually enduring. Released in May, "Fast & Furious 6" was the most lucrative of them all, grossing more than $788 million worldwide. The seventh installment began shooting in September, with a release planned for July.
"Your humble spirit was felt from the start," said Ludacris, Walker's "Fast & Furious" co-star, on Twitter. "Wherever you blessed your presence you always left a mark, we were like brothers."
Walker is survived by his 15-year-old daughter.