The Pershing County Sheriff's Office says it is investigating a suspicious death that occurred at Burning Man on Thursday. 

They say 33-year-old Shane Billingham was pronounced dead inside the medical tent inside Black Rock City. 

The Pershing County Sheriff's Office said a preliminary investigation from the Washoe County Medical Examiner's Office revealed the toxicology results "findings were suspicious for carbon monoxide poisoning." They said the Medical Examiner advised Billingham had a concentration of carbon monoxide in his blood which would be considered poisonous to human life.

Pershing County Sheriff's Office said comprehensive testing is still pending.

They also said the preliminary toxicology results showed the presence of controlled substances that were an exacerbating factor.

They said quantitative analysis of the toxicology will not be available for a few weeks.

Burning Man started last Sunday and will end on Tuesday. 

Last weekend, a Carson City man died while driving to Burning Man on SR 447 near Gerlach. An official cause of death remains pending in this crash. Washoe County Deputies say two people inside a RV suffered minor injuries. 

Then on Monday three people were injured in a plane that crashed at the Reno-Stead Airport that was believed to be returning from the playa. The FAA is investigating the incident.Â