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 blackout began when a transmission line at a substation in Havana shorted, triggering a chain reaction that caused the entire island's power generation to shut down. This incident marked the fourth nationwide blackout since October.

Millions of people in Cuba remained without power Saturday after a failure of the nation's electric grid left the island in the dark the previous night. The blackout is the fourth in the last six months as a severe economic crisis plagues the Caribbean country.