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.

Alanna Gladstone, a 40-year-old film editor, had landed in Portugal’s capital, Lisbon, on a flight from New York hours before the outage. She checked into her Airbnb and took a nap; by the time she woke up, the technology that the country takes for granted had gone dark.

A massive power outage appears to have affected large portions of Spain and Portugal Monday. Red Electrica, the operator of Spain's power grid, said on social media Monday morning that voltage has been recovered in substations in several areas in the north,