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 began returning to households in Spain and neighbouring Portugal, hours after cities across the Iberian Peninsula were plunged into darkness in one of Europe's most severe blackouts.Investigators are still looking into the cause of the blackout which remains unclear,

Officials for the Madrid Open cancelled Monday's play amid a blackout in Spain that impacted the tournament's facilities. The blackout caused a number of logistical problems at Caja Mágica with the scoreboards going dark and the loss of lighting to help fans navigate the venue: