Black Rock City (United States) (AFP) - Tens of thousands of festivalgoers were stranded Sunday in deep mud in the Nevada desert after rain turned the annual Burning Man gathering into a quagmire, with police investigating one death.

Video footage showed costume-wearing “burners” struggling across the wet gray-brown site, some using trash bags as makeshift boots, while many vehicles were stuck in the sludge.

All events at the counterculture festival, which drew some 70,000 people, were canceled after rain tore down structures for dance parties, art installations and other entertainment.

Police said they were probing one death, without giving further details.

Road gates in and out of the Black Rock City venue were closed, but some desperate attendees trudged on foot for hours to reach the nearest road and hitch a lift out.

“It was an incredibly harrowing six-mile (10 kilometer) hike at midnight through heavy and slippery mud, but I got safely out,” lawyer Neal Katyal said on social media.

“It is very slippery and the mud is like cement and sticks to your boots.

“No one should try this unless in good shape and part of a group. These are dangerous conditions to hike and will likely get worse.”

Festival crowds were asked to shelter in place and conserve food and water after the heavy rains started Friday night, with more downpours forecast on Sunday.

“You can’t really walk or drive,” a young woman named Christine Lee, a circus performer, said on TikTok. Internet service was either not available or patchy, she said.

“My boots are five inches, and the mud became five inches so I was kind of on stilts,” Lee said, adding people were being told they may be stuck until Tuesday.

“We have enough tuna for a week so we’re OK.”

- ‘Water and hope’ -

A video posted on social media showed comedian Chris Rock hitching a ride in the back of a pickup truck after managing to leave.

Pershing County Sheriff’s Sargent Nathan Carmichael told CNN the conditions are difficult.

The muck “seems to stick to people, stick to tires (and) makes it very, very difficult to move vehicles around,” he said, adding that most RV motorhomes were stranded.

Organizers urged festivalgoers to “conserve food, water and fuel, and shelter in a warm, safe space,” saying the “playa” – the huge open-air esplanade where the event unfolds – was impassable.

“Look out for your neighbors, introduce yourself,” they added.

One attendee, known on the playa only as Dr T, told AFP he is planning to “just go with the flow, meet people and make the best out of this difficult situation.”

The California surgeon said he was worried about missing patient appointments Tuesday, but that there was “nothing I can do about it right now.”

“We have water, and we have hope and we take people (into) our camp when they need” it, he added.

Organizers announced the event’s finale attraction – burning a structure known as “the Man” – was set to go ahead Sunday night, “weather permitting.”

The festival was scheduled to conclude on Monday.

- ‘Survival guide’ -

The organizers warned only some four-wheel drive vehicles with all-terrain tires were able to move.

“Anything less than that will get stuck. It will hamper exodus if we have cars stuck on roads in our camping areas, or on the Gate Road out of the city,” they said on a “2023 Wet Playa Survival Guide” special webpage.

If necessary, they said it was possible to walk to the nearest road, where buses would be provided to take people to Reno.

Mobile cellphone trailers were being deployed and the site’s wireless internet was opened for public access.

“We have done table-top drills for events like this. We are engaged full-time on all aspects of safety,” organizers said.

According to a White House official, President Joe Biden had been briefed on the situation in the desert.

“Event attendees should listen to state and local officials, and event organizers,” the official said, adding that the administration was in touch with local authorities.

Last year, the festival contended with an intense heat wave and strong winds.

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

The festival – for which tickets cost hundreds of dollars – 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.