Cuba's electrical grid collapsed Sunday for the fourth time in 48 hours, a major setback in the efforts to restore power to exhausted residents.

Tropical Storm Oscar is making it harder to restore power in Cuba after a massive, prolonged power outage that preceded the storm. Oscar is hitting a key region for power generation where at least two important power plants in the city of Holguín Santiago de Cuba are located.

Cuba has had four electric grid collapses since Friday, and most of the country remains in the dark as slow progress is made to restore power.