Portugal’s grid operator Redes Energéticas Nacionais (REN) said electrical supply was lost across the entire Iberian Peninsula, and in parts of France, shortly after midday. Hours later, Spain’s Prime Minister Pedro Sanchez said authorities were still not sure what caused the blackout.

A massive power outage has knocked out electricity across parts of Spain and Portugal, shutting off traffic lights and causing chaos at airports, train stations and on the roads.