Parts of Havana saw electricity return, though vast swaths of the city and country remained in darkness Sunday morning following a catastrophic grid failure that left 10 million people without power.

Havana’s electric company reported that roughly 19% of its customers had regained power but provided no timeline for a full restoration. The Ministry of Energy and Mines announced the reactivation of the Felton power plant, a crucial step in restoring electricity to Cuba’s eastern provinces, while the country’s largest facility, Antonio Guinteras in Matanzas, remained offline.

With nearly 36 hours of blackout, residents of Havana—home to two million people and a key tourist hub—worried about food spoilage as refrigeration ceased. Only major hotels, select restaurants, and businesses with private generators maintained power.

The outage began Friday night when a substation transmission line in Havana short-circuited, triggering a chain reaction that shut down power generation across the island. It marked Cuba’s fourth nationwide blackout since October, exacerbating an energy crisis fueled by aging oil-fired plants and dwindling fuel imports from Venezuela, Russia, and Mexico.

Even before the grid collapse, Cubans were enduring daily blackouts lasting up to 20 hours. The government attributes the crisis to the long-standing U.S. trade embargo and recent sanctions imposed by President Donald Trump, who has reinforced a hardline stance against the communist-led nation.

In response, Cuba is accelerating efforts to construct large-scale solar farms with Chinese assistance, aiming to lessen its reliance on outdated oil-based energy infrastructure.