Later, an outfit calling itself the Volcano Group claimed responsibility for the attack. In a statement published online, it dismissed sympathy for the residents of the affluent neighborhoods affected. There was no mention of the people whose lives it put at risk that morning. Germany’s federal prosecutor is now investigating the incident, and has informed Thomsen that he will be interviewed about his experience.
For investigators, the Volcano Group’s claim was both familiar and frustrating. The name had appeared repeatedly over the past decade in connection with acts of sabotage against rail networks, power lines and the construction site of Tesla’s first European gigafactory. The German Interior Ministry attributes at least 13 attacks to the group, but investigators believe that it is less an organization than a label — one adopted by different perpetrators.
Authorities suspect the January blackout is linked to a similar attack in September 2025, when unknown perpetrators set fire to two power pylons in southeast Berlin’s Johannisthal municipality. Their target was the electricity supply to the Adlershof technology park, one of the largest of its kind in Europe. Tens of thousands of households lost power, some for days. The damage ran into the tens of millions. Shortly afterward, a claim of responsibility appeared online, signed simply: “Some anarchists.”
At the time, the case seemed exceptional. In hindsight, investigators now see it differently. Security authorities believe the perpetrators of the Johannisthal arson attack and those behind the January blackout in southwest Berlin come from the same milieu: a loose, clandestine network of left-wing activists that has proven difficult for authorities to keep track of, let alone stop.
Through conversations with police officers, prosecutors, domestic intelligence officials and security policymakers, granted anonymity to speak frankly, WELT reconstructed many of the attacks in detail, as well as the ways law enforcement has responded. What emerges from police files and interviews is a fragmented picture. The network, German investigators interviewed by WELT said, is less an organization than a scene, a collection of fellow travelers coordinating in an ad hoc fashion.
Roles within the network are loosely divided. Some provide the ideological slogans: They write texts, deliver lectures and create the theoretical foundation for action. Others take on the operational side: small groups of siblings, childhood friends, kindred spirits. Meanwhile, left-wing publications outline grievances, justify attacks and, at times, describe in detail how to carry them out.
