A major power outage hit Spain on Monday, shutting down trains, airports and other critical infrastructure and causing chaos in cities across the country. Parts of Portugal and France were also affected by the blackout, which energy authorities said occurred following a disruption in the European grid.

It was not immediately clear what caused the outage, but the effects of the disruption were felt by millions of people across the Iberian Peninsula.

Hospitals in Spain were forced to run on generators. Portuguese banks and schools closed. Matches for the Madrid Open tennis tournament were suspended, the ATP Tour said.

In Murcia, a city in southeastern Spain, crosswalk signs and traffic lights went dark, though some still drove cars carefully through the streets.

“The interruption was due to a problem in the European electricity grid,” E-Redes, the national energy supplier of Portugal, said in a statement. In addition to Portugal, it said, “The blackout also affected regions of Spain and France, due to faults in very high voltage lines.”

E-Redes said that the outage was widespread across Spain, with outages in Catalonia, Andalusia, Aragon, Navarre, the Basque Country, Castile and León, Extremadura and Murcia.

In France, the Portuguese energy supplier said, “the Basque Coast and the Burgundy region also experienced power cuts.”

Spain’s national power company, Red Eléctricia, said in a post on X that it had already restored some power in the north and south of the peninsula.

António Leitão Amaro, the minister of state for the presidency in Portugal, said on national radio that there was no evidence of a cyberattack.

Renfe, the national rail company, wrote in a post on X that “at 12:30 p.m., the entire National Electricity Grid was cut off,” adding that trains had stopped operating at all stations.

Local trains are also affected. In southeastern Spain, Valencia’s local train service said in a post on X that traffic had been disrupted throughout its entire network: “The extent and duration of the outage are unknown.”

Daily life ground to a halt as cities reeled without electricity. Some restaurants in Murcia stopped serving food, and churches closed their doors. Long lines started to form at ATMs.

Teresa Garcia, 92, sat in a wheelchair outside her house around lunchtime. She was waiting for the power to return so the elevator could take her back up to her apartment, she said.

EasyJet, the airline, told passengers that “Spanish airports are currently experiencing ongoing power outages affecting multiple essentials systems and airport infrastructure.”

The airline said it expected delays and described the disruption as “extraordinary and outside of our control.”

With the midday sun shining brightly in Murcia, not all activities were curtailed. Indoor flamenco classes continued, as people practiced in the light streaming in from the windows.

This is a developing story. Check back for updates.