A pair of climate protesters were arrested Wednesday at the U.K.s Stonehenge monument after they sprayed the 5,000-year-old rocks with orange paint, British police said .

The protesters, 21-year-old Niamh Lynch and 73-year-old Rajan Naidu, are part of Just Stop Oil, a group that says it wants the British government to establish a legally binding treaty to stop extraction and burning of oil, gas and coal by 2030 alongside other nations.

With a national election set for July 4 , Just Stop Oil is demanding that the incoming British government take action to phase out fossil fuels within a six-year period.

The paint is allegedly cornstarch-based, and is supposed to wash away in the rain, although the area is not expected to see rain before the weekend.

The monument receives a swell of visitors each summer solstice. This years solstice is Thursday.