Tropical Storm Oscar doused Cuba on Monday, three days after a massive power failure plunged more than 10 million people into the dark as the island worked to restore its decades-old power grid.

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.