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 countrywide power outage impacted Spain—as well as swaths of Portugal and smaller portions of France—Monday afternoon, affecting essential services and wreaking chaos across the Iberian Peninsula. The cause of the outage is currently being investigated by Spanish and Portuguese officials and ministers.