Emergency medical services working on the Schleswig-Holstein site say a so-far unnamed festivalgoer lay down on a canvas-covered trailer, where he fell asleep.
Red Cross sources say a power generator was also underneath the cover and running, filling the space between trailer and canvas with carbon monoxide.
The festival immediately released a statement about the Aug. 4 incident, as the state attorney’s office opened an official investigation.
“We are shocked and send our condolences to family and friends of the deceased,” the statement said.
Early reports suggest that friends of the deceased, on noticing that they hadn’t seen him for a couple of hours, went looking for him. They discovered his lifeless body under the canvas on the trailer.
Emergency services and doctors were called immediately but weren’t successful in resuscitating him.
The tragedy happened as WOA, the world’s largest designated heavy rock fest, is heading for a bumper year. It sold out its 75,000 capacity by the end of November.
This year’s lineup Aug. 2-4 included Scorpions, Saxon, Machine Head, Volbeat, Ministry, Opeth, Danko Jones (spoken word), Hammerfall, In Flames and Leningrad Cowboys.