Power has now been fully restored in Spain and Portugal, as officials continue to investigate what caused the outage.

Electricity has returned to most of Spain and Portugal but with continued disruptions on the second day after an unknown failure caused a massive blackout across much of western Europe.

Luis Ibáñez Jiménez was driving on a highway in east Madrid when Spain lost power. “Suddenly, there were no traffic lights,” the resident of the capital told CNN. Cars piled up, and nobody had right of way.