Cuba’s national power grid went down on Friday, leaving about 10 million people on the island without electricity.
Cuban President Miguel Diaz-Canel said officials were giving “absolute priority” to fixing the problem.
“There will be no rest until he recovers,” he added.
The island’s government closed schools and “non-essential” industrial sites on Friday morning in a last-ditch effort to preserve supplies.
But shortly before noon, the Antonio Guiteras power plant – one of the of Cuba the largest – went offline, causing a complete network crash.
Officials did not go into detail about what caused the shutdown or say how long it might take to bring the site back online.
All “non-essential” government offices, along with schools and universities, are expected to remain closed until at least Sunday. Cultural and entertainment venues, including nightclubs, have also been ordered to close.
However, not everyone on the island was left without power.
Some homes and businesses, such as restaurants, have private generators.
To the USA Guantanamo Bay Naval Baseon the southeast coast of the island, is also considered unaffected as it has its own power supply.
This comes after continuous power outages across the country in recent weeks.
Cuban Prime Minister Manuel Marrero said on Thursday that the problems were caused by a combination of infrastructure problems, fuel shortages and rising demand, including from household air conditioners.
“The lack of fuel is the biggest factor,” he said in a televised address.
Residents of Havana interviewed by Sky News’ US partner NBC News expressed dismay at the latest outage.
One man told the broadcaster: “This is unbelievable. I don’t see a solution to this problem.”
One woman added: “It really worries me that we may not be at the bottom of this electricity crisis yet.”
Brazilian tourist Carlos Roberto Julio also expressed disappointment.
He told Reuters: “We went to a restaurant and they had no food because there was no electricity, now we are also without internet.
“In two days we already had several problems.
Read more from Sky News:
Hamas confirmed the leader’s death
Father and daughter commit suicide by catfish
British brackets for Storm Ashley
Officials said strong winds from Hurricane Milton last week hampered efforts by boats to deliver fuel needed to operate the power plants.
US trade embargo, along with sanctions introduced by former President Donald Trumphas also been blamed for cutting supplies of fuel and spare parts needed to repair machinery at Cuba’s power plants.
President Díaz-Canel said in a statement earlier this week: “The complex scenario we are going through has the main reason for the intensification of the economic war and the financial and energy persecution by the United States, which makes it difficult to import fuel and other resources needed for this industry.”
The White House hit back at the claims. A spokesman for the US National Security Council said: “The United States is not to blame for today’s blackout on the island or for the overall energy situation in Cuba.”
Cuba’s largest oil supplier, Venezuelaadded to the problems by cutting supplies to the island this year as it grapples with its own shortages.
Russia and Mexico also significantly reduced supplies to The Caribbean country.