BUDAPEST, Hungary (AP) — An unprecedented blackout across Spain and Portugal upended the lives of millions across the Iberian Peninsula, a stark reminder of modern society’s reliance on electricity, and how quickly life can descend into chaos when the grid goes down.

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