MADRID (AP) — The cause of Spain and Portugal’s widespread blackouts remained a mystery on Tuesday, with some isolated disruption remaining after power was largely restored. One of Europe’s most severe blackouts grounded flights, paralyzed train systems, disrupted mobile communications and shut down ATMs across the Iberian Peninsula on Monday.

Electricity is pulsing through Spain and Portugal again after a massive outage knocked out power in both countries on Monday. So too are questions.

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