Paul Walker, an actor best known for his role in the “Fast and the Furious” movies about street racing, died on Saturday in Valencia, Calif., when the Porsche he was riding in crashed in a single-car accident and burst into flames. He was 40.

His death was confirmed by his publicist, Ame Van Iden.

The driver of the car, who was also killed, was identified by The Los Angeles Times as Roger Rodas, a friend of Mr. Walker’s. The authorities did not identity the victims of the crash.

Speed was a factor in the accident, which occurred at 3:30 p.m., on Rye Canyon Loop in Valencia, about 30 miles northwest of Los Angeles, the Los Angeles County sheriff’s office said. Authorities said the vehicle, a red 2005 Porsche Carrera GT, was engulfed in flames when they arrived.

Earlier in the day, Mr. Walker had attended a charity event for the nonprofit of which he was a founder, Reach Out Worldwide, which provides relief efforts after natural disasters.

Athletic with blond hair and blue eyes, Mr. Walker often played the action star or the romantic interest. He starred in six of the seven “Fast and Furious” movies, often alongside the action star Vin Diesel, with the latest installment still being filmed and scheduled for release next year. The movies were popular and lucrative — the most recent one, “Fast and Furious 6,” grossed $788 million worldwide this year.

Paul William Walker IV was born in Glendale, Calif., on Sept. 12, 1973. He started acting at a young age and had a few prominent parts in the late 1990s, playing supporting roles in the films “Pleasantville,” “Varsity Blues,” and “She’s All That,” and starring in “The Skulls.”

But his big break came in 2001 with “The Fast and the Furious,” in which he played an undercover Los Angeles police officer investigating street racing. The $30 million film brought in $207 million. Sequels followed and continued to attract audiences with over-the-top car chases, but he had trouble finding major success outside the franchise.

Mr. Walker enjoyed racing and had a car collection that included a Porsche 911 GT3 and a1964 Chevrolet Impala, he said in an interview with Automobile magazine. He also helped run a luxury garage with friends in Valencia, near where the crash occurred.

Critics could be hard on Mr. Walker. In a 2003 review of the movie “Timeline” Stephen Holden described Mr. Walker in The New York Times as “a throwback to the days when imitation Tab Hunters were tapped for potential stardom simply on the basis of their dimpled smiles and vacant, sparkly eyes.”

Mr. Walker stayed out of the tabloids and away from the Hollywood party scene. He didn’t want to live in Hollywood, his publicist said, and settled instead in Santa Barbara.

In March, he told Entertainment Weekly that he didn’t feel entirely at ease in the limelight.

“I’ve always been one foot in, one foot out of this game because I’m not comfortable with being on the pedestal or the poster,” he said. “That’s just not who I am. I’m more like the grunt. I want to be the guy behind the guy.”

Recently, he had made a priority of spending more time with his 15-year-old daughter, Meadow, friends said. She had lived in Hawaii with her mother, Rebecca Soteros, for most of her life, but was now living with Mr. Walker.

In addition to his daughter, Mr. Walker is survived by his father, Paul Walker III; his mother Cheryl Walker; two brothers, Cody and Caleb; and a sister, Ashley.

Mr. Walker was proud of his forthcoming film, “Hours,” to be released this month, about a father who tried to keep his infant daughter alive during Hurricane Katrina, his friend and longtime agent, Matt Luber, said.

“In the end, it was a story about saving his daughter — I think that spoke to him,” Mr. Luber said. “And it was an opportunity to show people that he was more than just an action star.”