Fidel Castro once called Cuba’s power plants “prehistoric.” But the country still relies on them, contributing to the longest blackout since the collapse of its former patron, the Soviet Union.

Cuba's electrical grid collapsed again early on Saturday morning, state-run media reported, plunging the entire country into blackout for a second time just hours after authorities announced they had begun reestablishing service.

Cuba’s government says some electricity has been restored on the island after one of the country’s major power plants failed and left millions without electricity for two days