Utah officials say thousands attended a rave-like Halloween event that was advertised as a "protest" against coronavirus restrictions.
Utah County Sheriff's Office spokesperson Sgt. Spencer Cannon told NBC affiliate KSL that the number of people who attended the Saturday night party ranged "anywhere from three to ten thousand people"
The event took place at an area known as "The Knolls," located on the barren western shore of Utah Lake, opposite the city of Provo.
Cannon told NBC News that authorities discovered the unauthorized mass gathering when attendees requested medical assistance after a woman was knocked unconscious while crowd surfing. Cannon added that there were also two car accidents as attendees drove away. Police shut down the party at around 10:00 p.m. on Halloween night.
For weeks, party organizers Utah Tonight and the Tribe Utah had advertised a Halloween "protest" party at an undisclosed location to be announced on Halloween.
Earlier this month, The Tribe Utah said on Instagram that Utah Tonight would "keep the faces of everyone at the Protest on Halloween confidential so you have nothing to worry about! 😈😏 Remember, the Protest on Halloween is not our event. 😂🤷♂️"
Tribe Utah did not immediately respond to a request for comment, but argued on social media against coronavirus restrictions, saying "gatherings are essential for public health." Utah Tonight has similarly argued online against the public health provisions, saying they were "subjectively applied."
A spokesperson for Utah Governor Gary Herbert said in a statement that COVID-19 is mainly spread through social gatherings, and that the virus "is all too real and terrifying for the medical professionals working overtime in our packed ICUs."
"We must decide, and show by our actions, that the lives of everyone around us matter more to us than parties. If we do not, we will have a difficult time beating COVID-19 as a society," the statement said.
Utah is in the grips of a severe coronavirus outbreak, with Utah County and most others in the state experiencing a "very high rate" of coronavirus cases, according to the state health department's numbers.
A version of this story originally appeared on NBCNews.com.