Millions across Spain, Portugal, and parts of France were left in the dark on Monday as a mysterious power outage swept through the region, leaving residents uneasy and authorities searching for answers.

A massive power outage has plunged Spain and Portugal into darkness, knocking out key services and forcing the evacuation of subway systems in both countries.

Puerto Rico has plunged into darkness once more as a new islandwide power outage strikes, echoing the prolonged blackout from New Year’s Eve. Residents are again facing the challenges of life without electricity, raising concerns about the reliability of the island’s power grid.