BARCELONA, Spain >> A blackout brought much of Spain and Portugal to a standstill Monday, halting subway and railway trains, cutting phone service and shutting down traffic lights and ATMs for millions of people across the Iberian Peninsula.

Spain’s Prime Minister Pedro Sánchez said that a problem in the European grid that he described as a “strong oscillation” was behind the outage, but that the cause was still being determined. The Spanish leader asked the public to refrain from speculation and said no theory about the cause of the outage had been discarded.

Spanish power distributor Red Eléctrica said at the time that restoring power fully to the country and neighboring Portugal could take 6-10 hours.

— The Associated Press