Paul Walker's death certificate has ruled he died from ''combined effects of thermal and traumatic injuries''.

The official document, which was obtained by TMZ, concludes the late 'Fast & Furious' star not only suffered numerous injuries in the horrific car crash on November 30, but also burned to his death in the subsequent explosion.

Paul, who was 40 at the time of his death, and pal Roger Rodas were involved in the fatal accident after the 2005 Porsche Carrera GT they were in veered off the road and crashed into a lamppost.

While the actor's death certificate rules his death a combination of thermal and traumatic injuries, his pal's death has been determined to be the result of ''multiple traumatic injuries'', which means burning wasn't a factor in his demise.

According to the certificate, both men died quickly at the scene, with the coroner ruling the time between the incident and their deaths was ''rapid''.

Roger was driving the sports car at the time of the fiery accident in Santa Clarita, California, but local police believe it may take months to determine what caused the accident.

Detective Jeff Maag said recently: ''To the extent that we can, we need to rule out mechanical failure. But the car is a mess.''

Paul's body was cremated last Thursday (12.12.13) and he was laid to rest at the Forest Lawn Memorial Park in Los Angeles' Hollywood Hills on Saturday (14.12.13).

The service was attended by Paul's parents, his 15-year-old daughter Meadow, and his 'Fast & Furious' co-stars Michelle Rodriguez, Tyrese Gibson and Ludacris.