BLACK ROCK DESERT, Nev. (AP) — Authorities said Monday that they are investigating the death of a woman at the counterculture festival known as Burning Man, which is held annually in the northern Nevada desert.

The Pershing County Sheriff’s Office said emergency personnel responded to a call about a woman found unresponsive around noon Sunday in Black Rock City — a temporary city erected for the festival, about 100 miles (160 kilometers) north of Reno.

The Burning Man Project’s emergency services personnel were unsuccessful in attempted life-saving measures on the woman.

“Our thoughts and condolences go out to the family and friends affected by this loss,” festival organizers said in a statement. “We are cooperating fully with local authorities as they investigate this incident.”

Pershing County Sheriff Jerry Allen said in a statement that the death will remain under investigation until a cause and manner can be determined, which will be updated at the conclusion of an autopsy.

A call to the Washoe County Regional Medical Examiner’s Office wasn’t immediately returned Monday.

Allen said the woman’s name and age won’t be released until her relatives can be notified.

The festival kicked off early Sunday after the gates had been closed for 12 hours following rain and muddy conditions.

An estimated 20,000 people were already on the playa before the gates opened.

Burning Man runs through Sept. 2 with organizers expecting more than 70,000 people to attend this year’s event.

A 32-year-old man from California died last year after being found unresponsive on the festival grounds. Authorities said they suspected drug intoxication.

In 2023, the 35th annual Burning Man festival was attended by an estimated 73,000 people with an additional 95,000 participating in regional events around the world.

It was disrupted by a protest blockade that was shut down by local authorities and about a half inch of rain turned the playa into mud, making it difficult to drive and pedal bicycles.

Authorities brought in cell towers and asked attendees to stay put until the rain cleared.