MOSCOW (Sputnik) – The gas cylinder fell over at a camp at the festival site, causing a flash fire, according to the national De Standaard daily.
A press statement on the festival’s website said five people were taken to nearby hospitals and two others were treated on site.
"No one is in mortal danger," the statement read.
The annual Pukkelpop festival was held in the capital of Belgium’s Limburg province of Hasselt.