The cause of the power outage that severely disrupted life in Spain and Portugal on Monday remains a mystery as service was brought back to the Iberian Peninsula.

Electricity was restored to almost all of Spain and Portugal on Tuesday morning following a massive power cut affecting the entire Iberian Peninsula, but the cause of the blackouts remained a mystery.

Electricity was back in most of the two countries almost 18 hours after a blackout that shut down much of daily life. The cause of the outage remained unclear.