A power outage caused chaos at a train station in Madrid, Spain, on Monday afternoon. Footage shows distressed passengers stranded and overcrowding the terminals on April 28. Officials said the electricity cut was part of a major grid failure that impacted large parts of Spain and Portugal.

Power has been restored to tens of millions of people across almost all of Spain and Portugal, but disruptions to transport services were expected to stretch into a second day as questions mount over what caused a massive blackout.