The power grid in Germany's eastern state of Brandenburg came under a deliberate sabotage attack on September 1, with unexploded incendiary devices inflicting damage to power lines, according to Reuters, citing the state's interior minister Jan Redmann.

The incident joins a string of security events prompting German officials to review safeguards for critical infrastructure amid mounting risks of cyber and hybrid threats.

The targeted Turnow-Preilack substation serves as a key high-voltage hub, linking Brandenburg's large Jaenschwalde coal-fired power plant to the 50Hertz transmission network.

Projectiles loaded with conductive material were launched towards extra-high-voltage power cables and triggered two short circuits, Redmann said at a press conference. Investigators are combing through the scene; the tally of recovered devices is already in double digits and continues to climb.

Redmann declined to rule out foreign state actors as potential perpetrators, while also not eliminating left-wing activists, who have staged prior assaults against energy infrastructure. He stressed the rockets were custom-built hardware rather than ordinary fireworks and required considerable preparation to deploy.

"When it comes to our critical infrastructure, we in Germany are far too vulnerable," Redmann warned.

Grid operator 50Hertz reported multiple transmission lines sustained physical harm, triggering a short-lived outage. All affected circuits have since been brought back online, broader public power supplies remained stable and no casualties occurred.

Plant operator LEAG disclosed one generating unit at the Jaenschwalde coal-fired facility encountered a technical malfunction. Authorities are probing whether the fault is connected to the sabotage, and the unit has resumed operation later on September 1.

Brandenburg Minister President Dietmar Woidke condemned the act. "Anyone who tries to sabotage our critical infrastructure and paralyze society is attacking all of us," he commented.