Police say the area where Fast and Furious star Paul Walker died in a car crash is known to attract street racers.

Walker, 40, and his friend and financial adviser Roger Rodas died in the one-car crash Saturday in the Southern California community of Valencia.

The street where the crash happened forms a loop amid commercial buildings that is isolated from traffic, especially on weekends.

California Highway Patrol Sgt. Rick Miler calls the neighbourhood "a hot spot for street racers."

The Los Angeles County Sheriff's Department is still investigating, but already has said speed was a factor.

According to Walker's publicist, Walker was a passenger in the 2005 red Porsche Carrera GT when he and Rodas drove away from a fundraiser.

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.

Eerie accident

Because Walker is so closely associated with the underground culture of street racing portrayed in the popular film franchise, the accident had an eerie quality — a tragic end for a Hollywood hero of speed.

Fans of Walker gathered to leave flowers, candles and memorabilia from the action movies. His Fast and Furious co-star Tyrese Gibson broke down when he visited the crash site.

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A girl places flowers at the scene of the car crash where actor Paul Walker was killed northwest of Los Angeles. (Phil McCarten/Reuters)

"Paul is the heartbeat of this franchise and we're gonna see to it that his energy and presence lives on forever," Gibson later posted on his Instagram account.

Sheriff's deputy Peter Gomez said investigators were trying to determine how fast the car was travelling and what caused it to go out of control, including whether the driver was distracted or something in the road prompted him to swerve.

After the Porsche crashed into a light pole and tree, it burst into flames. The downed light pole had a speed limit sign of 45 miles (72 kilometres) per hour.

Walker rode the Fast and Furious franchise to fame, starring in all but one of the six action blockbusters, beginning with the first film in 2001. He had been on break from shooting the seventh instalment; production began in September and while much of the film has been shot, it's incomplete.

He is survived by his 15-year-old daughter.