Paul Walker died of 'traumatic and thermal injuries,' autopsy concludes

"Fast and Furious" star Paul Walker and his friend Roger Rodas died as a result of injuries sustained when the Porsche they were riding in crashed "with a fixed object" on Saturday, the Los Angeles Coroner's office ruled on Wednesday. Walker, 40, died from the "combined effects of traumatic and thermal injuries" and Rodas, 38, died from "multiple traumatic injuries."

Both deaths have been ruled to be accidental, the Coroner's office said Wednesday. Toxicology tests are still pending in both cases and could take up to eight weeks to complete.

Walker and Rodas were killed Saturday in Valencia, Calif., when the limited-edition Porsche Carrera GT they took for a spin crashed into a tree and a concrete lamppost. By the time Los Angeles Sheriff's Dept. responders arrived on the scene, the car was engulfed in flames and the two men inside were burned beyond recognition. 

A law enforcement official familiar with the crash investigation told NBC News on Monday that the car was traveling at approximately 40 to 45 mph when it came to a bend in the road where the speed limit drops to about 15 mph. The five-lane road has warning signs for drivers advising them to slow down as they approach the uphill curve where the accident happened.

The source told NBC News that the car was not believed to have been in a race with a second vehicle and that Rodas apparently lost control of his vehicle in that area, ending in the fiery accident. Additionally, Capt. Mike Parker of the Sheriff's Department told NBC News on Tuesday that there was no evidence of fluid leakage prior to the crash and that officers are investigating whether the Porsche may have been running on something other than regular gasoline. No eyewitnesses saw the car lose control, Parker added.

CNN posted a video on Tuesday obtained from nearby security cameras showing smoke billowing soon after the moment of impact. 

"Speed was a factor in the collision," Parker said. "The estimated speed is under investigation."

People magazine reported on Wednesday that the car "was doing well over 45 mph," according Los Angeles County Sheriff's detective Jeff Maag, who speculated it could be at least double that number. Maag told E! that he won't know the car's actual speed until he inspects the scene. He also said he hopes to inspect the car and secure a warrant to read what is on the car's event data recorder.

Rodas was Walker's friend and chief executive officer of Always Evolving, the actor's automotive shop in Valencia, just north of Los Angeles. The two men were at a charity event for Reach Out Worldwide, a first-aid organization Walker founded after the 2010 earthquake in Haiti. Proceeds from the car show and toy drive were earmarked for families affected by the typhoon in the Philippines and a tornado in Indiana.

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Paul Walker was ‘heart and soul’ of Reach Out Worldwide

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The actor's father, Paul William Walker III, said in a KNBC interview on Monday that Paul was "the most courageous" of his sons and that he usually liked to race his cars at the track because “the last thing I want to do is hurt somebody driving crazy, that’s the last thing I want to do.”

Andrew Blankstein of the NBC News Investigative Unit contributed to this report.