Spain and Portugal are racing the setting sun as they respond to a massive, unexplained power outage that knocked out traffic lights, caused chaos on roads and in airports, and threatened to plunge tens of millions of people into darkness on Monday.

BARCELONA, Spain (AP) — A major power outage hit Spain and Portugal on Monday, including their capitals, knocking out subway networks, phone lines, traffic lights and ATM machines. It is rare to have such a widespread outage there. Spanish generator Red Eléctrica said it affected the Iberian peninsula and the incident is being assessed.

Shops and restaurants in Madrid were plunged into darkness, and there are queues at cash points in Lisbon as card payments aren't working.