Thousands of people were ordered to shelter in place at the Burning Man festival in the western state of Nevada on Saturday after heavy rains turned the desert site into a mud pit and forced organizers to close the gates.

"Do not travel to Black Rock City!" Burning Man organizers tweeted, referring to the desert area where the alternative festival takes place.

"Access to the city is closed for the remainder of the event, and you will be turned away."

Organizers urged festivalgoers already on site to "conserve food, water and fuel, and shelter in a warm, safe space."

They said rain was unlikely to stop until Sunday night. The festival was scheduled to conclude on Monday.

Due to downpours, the "playa," the huge open-air esplanade where the event unfolds, was rendered impassable.

Last year, the festival contended with an intense heat wave and strong winds, which made the experience difficult for the "burners," as festivalgoers are known.

Launched in 1986 in San Francisco, Burning Man aims to be an undefinable event, somewhere between a celebration of counterculture and a spiritual retreat.

Initially organized on a San Francisco beach, Burning Man has become a structured festival, with a budget of nearly $45 million (2018 figures) and over 75,000 participants at the last edition, down from the previous one in 2019.

The festival culminates each year with the ceremonial burning of a 40-foot (12-meter) effigy.

It has been held since the 1990s in the Black Rock Desert, a protected area in northwest Nevada, which the organizers are committed to preserving.

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