"In the barn for 90 dairy cows, methane built up for unknown reasons and was probably ignited by a static discharge, exploding in a darting flame," said local police in the central town of Rasdorf in Hesse state.
"Parts of the roof cover were slightly damaged and a cow suffered minor burns," said police, adding that a fire crew rushed to the scene of yesterday's accident and a gas field crew later measured methane levels.