Three roads in Hamburg were blocked at the same time, starting with an obstruction of the main tunnel under the Elbe river on Thursday morning, according to officials. One activist tried to glue themselves to the road, but was dragged away by police.

The climate change group defended its actions and said that "we have to pull the emergency brake, because continuing the way we are is killing us."

Police officials have now reopened Hamburg's Elbe tunnel and the Elbe bridges, however traffic was backed up for several kilometers after the incident.

"The clean-up and deployment activities at the Elbe tunnel are complete," police announced by early Thursday afternoon.

One of the affected roads heading north towards the cities of Flensburg and Kiel was blocked by a truck. Police had to fence off the entire road in order to remove the truck.

Meanwhile, five Last Generation activists glued themselves to the road ahead of the bridge crossing the Elbe. Authorities were able to prevent activists from doing the same on a parallel bridge.

"Without a rapid change of course, we won't simply mourn a few holiday destinations — we will be faced with the collapse of our economy, our food supply and ultimately our democracy," activists said.

Who are the 'Last Generation'?

The climate activist group calling themselves Last Generation (Letzte Generation in German) say they use civil disobedience acts to draw public attention to the climate change emergency. They also tend to seek both maximum disruption and also the most exposure possible.

This often involve either gluing themselves to roads or to certain public buildings, or in 2022 in particular the group and similar ones around Europe took to regularly throwing food or liquid on famous artworks in museums.

They also organized the major protests against the expansion of a western German open-face coal mine late last year attended by Greta Thunberg.

Some groups, including the German branch of WWF, have questioned whether these methods might be counterproductive, either because they risk asociating climate protests with more extreme measures or because they risk losing support for the cause among more moderate members of the public.