Methane gas from 90 farting and burping cows exploded in a barn on a German dairy farm on Monday.
High levels of the gas had built up in the structure in the central German town of Rasdorf, then "a static electric charge caused the gas to explode with flashes of flames," a police spokesman said.
A spark, probably triggered by a massage machine in the barn, ignited the methane and started the blaze.
Firefighters and a gas field crew were called to the scene. The roof of the barn was damaged, with one cow suffering minor burns.