Red Eléctrica, Spain’s electricity grid operator, ruled out a cyberattack, human error or unusual weather. Experts say it could take weeks to determine the cause.

Power is almost fully restored in Spain and Portugal a day after a major blackout. 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 to both countries.

Even as electricity was restored across Spain and Portugal after a daylong blackout, residents tried to make sense of 18 hours of the “insanity.”