Power Is Largely Restored in Spain After Widespread Outage

Spain’s national power company said early Tuesday that nearly all power had been restored in the country, mostly ending a major outage that affected airports, trains, traffic lights and other critical infrastructure.

The company, Red Eléctrica, said that 99 percent of power demand in Peninsular Spain was being met, and that all substations on the grid were operational by 6 a.m. local time, nearly 18 hours after power was shut off on Monday.

Peninsular Spain comprises a vast majority of the country’s territory on the Iberian Peninsula, where the blackout also hit neighboring Portugal.

The electricity and gas supplier in Portugal, REN, said late on Monday that it had restored 85 of its 89 substations and switching stations powering the country’s grid. But some regions remained in the dark, it said.

The cause of the blackout, which stranded tens of millions of people on the Iberian Peninsula, remained unknown early Tuesday, though officials said there were no signs of foul play, such as a cyberattack.

This is a developing story.