Climate activists broke through a police line and stormed a mine in western Germany on Saturday to protest against coal mining and demand action against climate change.
Police from the nearby city of Aachen used pepper spray to try to stop the activists. Eight police officers were injured.
Police would not confirm how many people had entered the mine. A spokeswoman for the activists estimated their numbers at 1,000.
Michael Mertens, head of the police union for North-Rhine Westphalia, accused the activists of "unbelievable carelessness." The edge of the mine was dangerous because the ground was unstable and not easily visible. "You can plunge 40 metres," he said.
The action was organised by the "Ende Gelaende" group, which led a separate march of some 1,600 people and earlier in the day had promised to "stream through" the police line.
Four out of six production units of the mine, which is Germany's largest, were shut down for security reasons by the owner, energy giant RWE.
"This is an intrusion into public utility infrastructure," an RWE spokesman said.
Australian Associated Press