Electrical power was fully restored to southwest Berlin on Wednesday, ending a five-day blackout that crippled the city’s affluent suburbs and triggered a major national security investigation. The outage, which left approximately 45,000 households and 2,000 businesses in darkness during a period of sub-zero temperatures, is now being treated by German authorities as a deliberate act of domestic terrorism.
The crisis began in the early hours of Saturday, January 3, 2026, when a sophisticated arson attack targeted a cable bridge over the Teltow Canal. The bridge carries vital high-voltage lines connected to the Lichterfelde power plant, a critical node in the capital's energy infrastructure. The resulting blaze severed supply lines to the districts of Zehlendorf, Wannsee, and Nikolassee, forcing hospitals to rely on emergency generators and leaving tens of thousands without heating or hot water.
Germany’s Federal Prosecutor’s Office announced Tuesday that it had assumed control of the criminal investigation. A spokesperson for the office confirmed the case is being pursued on charges of membership in a terrorist organisation, unconstitutional sabotage, and the disruption of public services. Investigators noted that the perpetrators likely used publicly available infrastructure maps to identify a "high-impact" vulnerability in the grid.
Berlin’s Governing Mayor, Kai Wegner, condemned the incident in a press conference following a visit to the affected areas. Wegner categorised the event as a calculated assault on human life. "We have experienced a terrorist attack in this city—a left-wing terrorist attack," Wegner stated. "This was not a minor arson attack, nor was it sabotage. It was a terrorist act that knowingly put lives at risk, especially those of patients in hospitals and the elderly."
Responsibility for the attack was claimed by the "Vulkangruppe" (Volcano Group), a far-left extremist organisation known for previous strikes against energy and transportation infrastructure. In a 2,500-word manifesto published online, the group characterised the blackout as an "action in the public interest" aimed at the "fossil-fuel-based energy" sector. While the group offered an apology to less affluent residents caught in the outage, the letter expressed specific hostility toward the "wealthy" residents of Berlin's southwest.
Franziska Giffey, Berlin’s Senator for Economic Affairs, described the attack as a "serious blow" to the city's resilience. "The question is whether these are merely left-wing activist groups acting out of ideological motives, or whether there is more behind it," Giffey said during an interview with public broadcaster RBB. She emphasised that the incident has exposed the urgent need for a more consistent political and security-related response to infrastructure threats.
The restoration process was hampered by heavy snowfall and frozen ground, which complicated the replacement of damaged underground cables. Utility operator Stromnetz Berlin deployed around-the-clock repair crews, ultimately restoring the final 20,000 homes ahead of the original Thursday estimate. Despite the return of power, several schools and nurseries in the Steglitz-Zehlendorf district will remain closed until next week as a precautionary measure while technical checks continue.
The incident has reignited a fierce debate within the Bundestag regarding the protection of Germany's decentralised energy grid. Security experts warn that the Vulkangruppe, which has previously targeted Tesla’s Gruenheide factory and railway signalling systems, is part of a growing trend of "infrastructure-focused" extremism. Federal officials are now reviewing security protocols for hundreds of similar "critical nodes" across the country to prevent copycat attacks.
