A 39-year-old woman died on the first day of Burning Man, the popular counterculture festival held annually in the Nevada desert, authorities said.

The woman, Kendra Frazer, was found unconscious on the festival grounds around 11:30 a.m. on Sunday and attempts to resuscitate her were unsuccessful, Burning Man organizers said in a statement.

Her cause of death is currently under investigation pending an autopsy and toxicology tests, Pershing County Sheriff Jerry Allen said in a statement shared on Facebook.

“Our thoughts and prayers are with Kendra’s family and friends,” Allen said.

The death occurred before the official start of the event, which festival organizers confirmed began at 6 p.m. Participants were allowed to enter the festival grounds at midnight on Sunday.

“It is with a heavy heart that the Burning Man Project confirms the death of a participant at Black Rock City in Nevada’s Black Rock Desert,” festival organizers said in the statement. “We understand this news will be difficult for many in our community.”

Burning Man is a nine-day festival focused on community and art, culminating in the symbolic burning of a large wooden mannequin. The event takes place in northwest Nevada’s Black Rock City, a temporary city built in the Black Rock Desert.

The festival began early Sunday after the gates were closed for 12 hours due to bad weather, The Guardian reported.

Before the gates opened, around 20,000 festival-goers were on Playa Playa – an alkaline salt pan of silt – and according to The Guardian, organizers are expecting more than 70,000 visitors to the nine-day event.

In recent years, festival visitors have died at the Burning Man Festival.

Leon Reece, a 32-year-old man from California, died last year after being found unconscious on the festival grounds. Authorities said drugs were the suspected cause of death.

In 2017, 41-year-old Aaron Joel Mitchell of Oklahoma died after jumping into a giant, burning puppet.

Every summer, tens of thousands of people, including celebrities such as Paris Hilton, Heidi Klum and Cindy Crawford, travel to the Nevada desert for the festival.

The event stalled last year when thousands of festival-goers, including several A-list celebrities, were stranded in the mud due to a rainstorm.

Chris Rock and DJ Diplo walked ten kilometers through the mud before a fan offered them a ride on a truck.