Power had almost fully returned to Spain early Tuesday morning as many questions remained about what caused one of Europe's most severe blackouts across Spain and Portugal.

A widespread power outage hit Spain and Portugal, affecting millions of people who live across Europe's Iberian Peninsula.

BARCELONA, Spain (AP) — A major power outage has been reported in Spain and Portugal, including their capitals. Spanish generator RedElectrica says the Iberian peninsula was affected. It says the incident is being assessed and responded to.