The collapse follows nationwide blackouts last year that plunged Cuba's frail power-generating system into disarray.

Pockets of Cuba's capital Havana saw the lights flicker back on though vast areas of the city and country continued without electricity on Sunday morning, after a nationwide grid collapse that knocked out power to 10 million people.

The collapse plunged the island nation of more than 11 million people into total darkness. It's the latest in a series of failures in the country's creaking, soviet-era infrastructure.