Hundreds of police began clearing climate protesters out of an abandoned village on Wednesday in a showdown over the expansion of an opencast lignite mine that has highlighted tensions around Germany’s climate policy during an energy crisis.

The protesters formed human chains, made a makeshift barricade out of old containers and chanted “we are here, we are loud, because you are stealing our future” as police in helmets moved in. Some threw rocks, bottles and pyrotechnics. Police also reported protesters were lobbying petrol bombs.

The demonstrators, wearing masks, balaclavas or biosuits, have been protesting against the Garzweiler mine, run by energy firm RWE (RWEG.DE) in the village of Lutzerath in the brown-coal district of the western state of North Rhine-Westphalia.

Climate activist Greta Thunberg plans to join the demonstration on Saturday, a spokesperson for Luetzerathlebt environmentalist group told Reuters.

Economy Minister Robert Habeck of the Greens called for no further violence after police and protesters scuffled.

“Leave it at that - from both sides,” he told reporters.

Police say the standoff could take weeks to resolve.

As the officers moved in, some activists perched on the roofs or the windows of the abandoned buildings, chanting and shouting slogans.

Others hung suspended from wires and wooden frames, or were holed up in treehouses to make it harder for police to dislodge them after a court ruling allowed for the demolition of the village now otherwise empty of residents and owned by RWE.

Julia Riedel, who said she has been camping in the village for two-and-a-half years, said the demonstrators had taken up their positions “because the issue here is whether the climate will cross the tipping point or not.”

Police, who had water cannon trucks on standby, led away and carried some protesters from the site.

The project has underscored Germany’s dilemma over climate policy, which environmentalists say has taken a back seat during the energy crisis that has hit Europe after Russia’s invasion of Ukraine, forcing a return to dirtier fuels.

It is particularly sensitive for the Greens party, now back in power as part of Chancellor Olaf Scholz’s coalition government after 16 years in opposition. Many Greens oppose the mine’s expansion, but Habeck has been the face of the government’s decision.

“The empty settlement of Lutzerath, where no one lives any more, is the wrong symbol in my view,” Habeck said with reference to the demonstration.