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.