Climate protesters on Sunday threw mashed potatoes at a Claude Monet painting in a German museum to protest fossil fuel extraction, AP reported.

Two activists from the group Last Generation, which has called on the German government to take drastic action to protect the climate and stop using fossil fuels, approached Monet’s “Les Meules” at Potsdam’s Barberini Museum and threw a thick substance over the painting and its gold frame.

The group later confirmed via a post on Twitter that the mixture was mashed potatoes. The two activists, both wearing orange high-visibility vests, also glued themselves to the wall below the painting.

In total, four people were involved in the incident, according to German news agency dpa.

A Barberini Museum spokesperson told dpa the museum had yet to determine whether the painting, part of Monet’s “Haystacks” series, might have suffered long-term damage.

The British group Just Stop Oil threw tomato soup at Vincent van Gogh’s “Sunflowers” in London’s National Gallery earlier this month.