A massive power outage paralyzed Spain and Portugal on Monday in an incident with no immediate explanation.
“It’s best to not speculate. We will know the causes soon. We are not discarding any hypothesis, but right now, we just focus on what’s most important: returning electricity to our homes,” Spanish Prime Minister Pedro Sánchez said at a news conference Monday.
The stoppage, which occurred about 12:30 p.m. Madrid time, caused chaos across the Iberian Peninsula and showed the vulnerability of Europe’s electrical grid — even on days without extreme weather or spiking demand. 
Trains stopped running. Hospitals canceled surgeries, according to news agencies, and depended on backup generators. Business ground to a halt as machines were unable to process credit card transactions. The outage even suspended several Madrid Open tennis matches, with photos showing a court with nonfunctioning scoreboards and darkened stands. Sánchez urged citizens to restrict cellphone use and to call emergency dispatchers only “when it is really necessary.”
By about 5:30 p.m. Madrid time, Red Eléctrica, the corporation that operates Spain’s electricity grid, said some power had been restored across corners of the peninsula, including parts of Catalonia, the Basque Country and Andalusia. About two hours later, the utility provider said more than a fifth of the peninsula’s power had been recovered. Full recovery may take up to 10 hours, Red Eléctrica told Spanish news outlets, which means the country’s power could be restored some time late Monday.
“Causes are being analyzed, and all resources are being dedicated to addressing the issue,” Red Eléctrica said in a statement.
More than 50 million people live on the Iberian Peninsula, but authorities did not provide an immediate estimate for the number of people affected by the outage. Portugal’s national grid operator described it as a “massive cut” in electricity supply across the peninsula. Data from Red Eléctrica showed a sudden plunge in electricity demand from about 27,000 megawatts to less than 13,000. Levels remained abnormally low two hours later.
Spain’s Energy Ministry said in a statement that Sara Aagesen, a deputy prime minister, visited the Red Eléctrica control center to “learn about the situation firsthand and monitor the incident.”
“All necessary measures will be put in place to restore normality as quickly as possible,” the statement said.
Prime Minister Sánchez also held a meeting at the control center, with Aagesen and several other ministers present, the Spanish newspaper El País reported, and Spain’s National Security Council called a meeting to address the outage.
Portugal’s Lusa News Agency said the country’s cybersecurity center had seen no evidence so far that the blackout stemmed from a cyberattack. Separately, the Reuters news agency quoted unnamed officials as saying a cyberattack had not been ruled out.
The Spanish grid also connects with Morocco, France, Andorra and Portugal. Spain and France experienced a major blackout on July 24, 2021, but it lasted less than an hour.
Previous power outages in Europe have been caused by technical problems, lightning strikes and damaged cables. In 2003, Italy faced a huge blackout because a tree was too close to a power line, resulting in a flashover, or a jump of electricity from the line to vegetation.
