Power was restored to some pockets of Havana, Cuba's capital, on Sunday morning, following a nationwide grid collapse that left 10 million people without electricity.

Despite this, vast areas of the city and the country remained in darkness.

Havana's electric company reported on social media that approximately 19% of the city's clients had regained power, but it offered no estimate for when full recovery would occur.

The Cuban Ministry of Energy and Mines confirmed that it had activated the Felton power plant, one of the country’s largest, to help restore electricity to the eastern provinces. However, the ministry stated that the country’s largest power plant, Antonio Guinteras in Matanzas, had not yet been brought online.

For many residents of Havana and other affected areas, the ongoing outage posed a growing concern. "The clock was ticking," as some worried that the scarce stock of frozen foods would spoil after approximately 36 hours without power.

The city of Havana, with its two million residents and as a major tourism hub, had been without electricity since around 8:15 p.m. (0015 GMT) on Friday. Only certain tourist hotels, a few restaurants, and homes and businesses with their own generators managed to keep their lights on.

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.

Cuba's oil-fired power plants, which have struggled with ageing infrastructure and dwindling oil imports from Venezuela, Russia, and Mexico, had already faced a crisis before Friday’s collapse. Many residents had been experiencing daily blackouts of up to 20 hours or more.

The Cuban government blamed the persistent energy crisis on the Cold War-era US trade embargo, which was further tightened under the administration of former US President Donald Trump. The government has since focused on developing large solar farms with the assistance of China to reduce its reliance on outdated oil-fired power plants.