Tens of thousands of people who spent days stranded at the Burning Man festival have started to leave, creating a huge traffic jam in the Nevada desert.
Heavy rain created a mud bath at the remote festival site and flooded roads, trapping some 72,000 people there.
Traffic was allowed to leave as of Monday afternoon which prompted a mass exodus from the site.
The wait time to leave the festival was five hours as of Tuesday morning.
And there were reports of high tensions in the queue.
In a statement sent to the San Francisco Chronicle, Pershing County Sheriff Jerry Allen said that exhausted revellers had "lashed out" at each other while stuck trying to leave.
He added that "large amounts of property and trash" had been strewn around the festival site, including vehicles that had to be abandoned.
"Some participants were unwilling to wait or use the beaten path to attempt to leave the desert and have had to abandon their vehicles and personal property," he said.
The event's traditional finale - the burning of an effigy - was postponed twice before finally taking place on Monday evening.
The rainstorm that hit the Black Rock Desert near the end of last week is thought to have been the longest, heaviest rainfall since the festival began more than 30 years ago.
Martyna Sowa, a dancer who was booked to perform at the event, told BBC Radio 4's Today programme that she was surprised at how bad the conditions became.
"It was a really strange experience," she said.
Revellers, who are expected to be largely self-sufficient as part of the festival's ethos, were told to take shelter and to conserve food, fuel and water.
But the bad weather meant the portable toilet facilities were temporarily out of use, because service vehicles were unable to drive on the mud to empty them.
While many remained on site, some chose to hike 5 miles (8km) through the mud to the nearest road. Among them was American DJ Diplo and comedian Chris Rock, who were given a lift by fans after walking out of the area over the weekend.
Others took the boggy conditions it in their stride - dancing in the mud and holding karaoke parties. "I'm having a great time," Jazz Korona told the BBC.
By Sunday, however, the sense of exhilaration had been replaced by a growing air of exasperation with people increasingly keen to leave.
Faye, a Burning Man participant who lives in London, told the BBC she had been "covered in mud for the past three days".
"There are no showers here," she said. "The only thing you can do is wash with baby wipes inside your tent."
The unusual rainstorms came towards the end of the nine-day festival, when the biggest crowds arrive to see the grand finale - the burning of the giant wooden effigy.
Organisers said a man's death on Friday was unrelated to the weather conditions.
Emergency services were called to help the man, said to be about 40 years old, but he could not be resuscitated, they said. The local sheriff's office .
Burning Man is one of America's most well-known arts and culture events, in which visitors create a temporary city in the middle of the desert.
It was founded in June 1986 and was first held in Nevada's Black Rock Desert in 1990.
Tickets can be very hard to get, and festivalgoers sometimes interview to get into popular camps and have to prove their commitment to its ideals.