Tesla Founder Elon Musk directed criticism at a group who appeared to claim responsibility for a suspected arson attack Tuesday on Europe’s only Tesla factory in northeastern Germany.

“[U]nknown perpetrators deliberately set fire to a high-voltage pylon between Steinfurt and Hartmannsdorf in the early morning of March 5th,” the State of Brandenburg’s Interior Ministry said in a statement. “The fire damaged the high-voltage power line so much that the power supply to the surrounding towns and the nearby TESLA factory failed.”

Power outages from the suspected arson attack affected some 2,000 households across various districts in Berlin, Deutsche Welle (DW) reported.

Vulkangruppe, or Volcano Group, appeared to claim responsibility for the attack on the electric power supply to the Tesla Gigafactory in Grünheide near Berlin, according to a missive signed by “Agua de Pau.” Police are aware of the letter and trying to confirm its authenticity, according to the New York Post.