Millions of people in Spain, Portugal and parts of southern France lost power on Monday following a "severe disruption" in the European electrical system, the Spanish prime minister said. The cause of the disruption is still unknown,

Play was halted at the Madrid Open tennis tournament, while the Spanish capital's metro system ground to a stop.

A massive power outage paralyzed much of Spain and Portugal, grounding flights, halting public transport, and disrupting hospitals, before power was gradually restored. The cause remains unclear, with Spain and Portugal blaming faults in their electricity grid connections.