The movie studio that makes the Fast and Furious action franchise said Tuesday it was suspending production of the latest instalment, while authorities pressed ahead with their investigation into how Paul Walker died.

The Los Angeles County coroner's office said autopsies were underway on the two bodies recovered from the fiery crash of a Porsche that Walker, a star of the mega-hit movies, and his friend were last seen riding in.

Walker's publicist has said the actor was the passenger when Roger Rodas' Porsche Carrera GT crashed into a light pole and tree, then exploded in flames Saturday.

The families of both men have provided dental records, which will permit not only formal identification of the bodies, but also official word on whether Walker or Rodas was behind the wheel.

Walker starred in all but one of the six Fast and Furious blockbusters. He had been on break from shooting the latest instalment; Universal Pictures said Tuesday that production of Fast and Furious 7 is on hold. A spokesman declined to say when shooting would resume.

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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)

A large portion of the film has been shot, but it is not yet complete. It's scheduled for release in July. Universal Pictures has not announced how it will adjust the movie or handle Walker's unfinished performance.

While the neighbourhood where the crash happened is known to attract street racers, law enforcement officials do not believe the Porsche he and a friend were riding in had been racing another car.

Accident investigators "have received eyewitness statements that the car involved was travelling alone at a high rate of speed," the Los Angeles County Sheriff's Department said in a statement Monday. "No eyewitness has contacted the (department) to say there was a second vehicle."

Fans hinder investigation

Hindering the accident investigation has been the crowds of fans that flocked to the crash site to leave flowers, candles and memorabilia from the action films.

On Monday night, a private memorial for survivors and the cast and crew of the Fast and Furious movies was held inside a white tent erected around the crash site. When it was over, Walker's co-star Vin Diesel emerged to thank fans for paying their respect to the actor.

"Thank you for coming and showing that angel up in heaven how much you appreciated him," Diesel said to the crowd, using the bullhorn of a police cruiser.

Rodas, 38, and Walker, 40 had taken what was expected to be a brief drive away from a charity fundraiser and toy drive at Rodas' custom car shop in Valencia, about 48 km northwest of Los Angeles.

The crash happened on a street that forms a loop amid industrial office parks. It is rimmed by hills and relatively isolated from traffic, especially on weekends when the businesses are closed.

"It's well-known out here that that's a hot spot for street racers," California Highway Patrol Sgt. Rick Miler said.

Skid marks are a testament to past antics on the loop. The sheriff's department, which polices the neighbourhood, said Saturday's wreck was not the first speed-related crash there, but would not reveal specifics.

Meanwhile, investigators are consulting video from security cameras, talking to witnesses and analyzing physical evidence such as on-board computer data from the Porsche.

Walker and Rodas had bonded over their shared love of fast cars.

The pair co-owned an auto racing team named after Rodas' shop, Always Evolving. Rodas was a financial adviser as well as a professional driver who competed in 10 Pirelli World Challenge GTS races in 2013. He finished second in rookie of the year standings, circuit spokesman Dave Drimmie said.