Power went down Monday afternoon in vast areas of Spain, crossing over into Portugal and France causing widespread outages in homes and businesses and bringing transportation infrastructure to a halt. The cause of the outage is currently unknown. Lisbon, Madrid, Seville, Barcelona, and Valencia are reportedly affected. The outage began at around 12:30PM CET.

Play has been suspended at the Madrid Open tennis tournament, according to Sky News. Madrid’s underground rail system has reportedly been evacuated and traffic lights in the city aren’t operating. Air traffic in Spain and Portugal is also reportedly affected by outages at area airports.

Red Eléctrica, Spain’s national electricity system operator, said it’s working with energy companies to restore power in regions that are affected by the outage. “We are beginning to recover power in the north and south of the peninsula, which is key to gradually addressing the electricity supply,” the company said in its most recent statement.