Witnesses reported seeing a red Porsche carrying "Fast and Furious" actor Paul Walker burning on a Santa Clarita street Saturday, killing the actor and another person.

"It was engulfed in flames. There was nothing. They were trapped," Antonio Holmes told the Santa Clarita Valley Signal. He added the actor had been at a charity event earlier in the day.

The single-vehicle crash occurred about 3:30 p.m. in the 28300 block of Rye Canyon Loop.

The cause of the crash is under investigation, Sheriff’s Deputy Kim Manatt told The Times. Few details about how the crash occurred were available, but officials were investigating whether speed was a factor.

Holmes said the Porsche appeared to hit a tree and then slam into a light standard.

Photos: Paul Walker: 1973-2013

According to a statement on his Twitter account, Walker, 40, was attending a charity event to aid Filipino victims of Typhoon Haiyan for his organization Reach Out Worldwide, formed in 2010 as a quick response first-aid organization.

“It is with a truly heavy heart that we must confirm that Paul Walker passed away today in a tragic car accident while attending a charity event for his organization Reach Out Worldwide,” the statement read. “He was a passenger in a friend's car, in which both lost their lives. We appreciate your patience as we too are stunned and saddened beyond belief by this news.”

PHOTOS: Celebs react to the death of Paul Walker

Representatives with Universal Pictures confirmed Walker’s identity and released a statement:

“All of us at Universal are heartbroken. 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. We send our deepest and most sincere condolences to Paul's family.”

At the time of his death, Walker, who also starred in "Pleasantville" and "Varsity Blues," was working on the seventh film of the “Fast and Furious” franchise.

There was a growing memorial at the crash site as people paid their respects.

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Twitter: @CarlaRiveralat

carla.rivera@latimes.com