Ryan Dunn Ryan Dunn

The preliminary autopsy results are in for Jackass star Ryan Dunn and his passenger, production assistant Zachary Hartwell. The Chester County Coroner's Office says that each man died as a result of either blunt force trauma or a fire that consumed Dunn's Porsche during the car crash in West Goshen Township, Pa., on Monday morning, TMZ reports.

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The violence of the accident makes it difficult to determine whether it was the impact or the fire that was the cause of death. Both men were dead once officials arrived at scene.

Toxicology results, which will help determine if alcohol was a factor in the crash, will not be released for another 4-6 weeks.