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,

Spain, Portugal and parts of France were plunged into chaos after power outages grounded flights, stopped trains and left whole cities without electricity or phone signal.

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.