Spain's investigation into the power outage that blacked out the entire Iberian Peninsula this week continued Thursday as top security officials met Wednesday.

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

Spain and Portugal are still reeling from the largest power cut in recent European history, which struck just after midday on Monday. With power supplies mostly back to normal, attention is laser-focused on what caused the incident.