The Pershing County Sheriff's Office in northern Nevada announced the death, which it said happened "during this rain event."
People walk through the mud at Burning Man in Black Rock City, Nev., on Saturday.
Attendees of the weeklong countercultural music and arts festival were first advised to "shelter in place" and conserve food and water on Friday, according to notices from organizers.
Some Burning Man attendees began trickling out of the festival on foot Saturday, authorities said.
Burning Man is an event of self-expression that culminates in the torching of a 40-foot effigy.
“If you are in BRC, conserve food, water and fuel, and shelter in a warm, safe space,” organizers continued to warn Saturday.
Carmichael of the sheriff's office said organizers, his county, the Bureau of Land Management, and other officials were prepared if rain on Sunday is heavy and more mud locks in attendees. »