On September 2, 2017, Mitchell ran through a safety perimeter at Burning Man and ran into the fire of the massive burning effigy at around 10:30 p.m local time.  He was rescued by on-site fire personnel and transported by air to UC Davis Medical Center.    
Background of Burning Man
Burning Man is an annual gathering that started in the late-1980s and currently takes place at Black Rock City, a temporary community erected in the Black Rock Desert in Nevada about 100 miles north of Reno. The event is described as an experiment in community and art, and is attended by tens of thousands of people every year.