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 re-establishing service.

CubaDebate, one of the island's state-run media outlets, said Cuba's grid operator, UNE, had reported at 6:15 a.m. ET the "total disconnection of the national electro-energetic system."

"The Electric Union is working on its re-establishment," the brief message said.

Cuba's electrical grid first collapsed around midday Friday after one of the island's largest power plants failed, suddenly leaving more than 10 million without power.

On Friday evening, several Canadian companies that bring tourists to Cuba, including Air Transat and Sunwing, said the outage has not been an issue for their own operations. 

Air Canada, in an email statement Saturday morning, said airports and hotels have been running on generators since the outage began. "We have no flight to or from Cuba today," it said.

Global Affairs Canada said it's "closely monitoring" the situation and will provide consular assistance to Canadians who need it.

Workers, students sent home

Even before the grid's collapse, an electricity shortfall on Friday had forced Cuba's communist-run government to send non-essential state workers home and cancel school classes for children as it sought to conserve fuel for generation.

But lights began to flicker on in scattered pockets across the island early in the evening on Friday, offering some hope that power would be restored.

The grid operator has not yet provided any details on what caused the grid to collapse again on Saturday, or how long it will take to re-establish service.

Cuba's government has blamed weeks of worsening blackouts — often 10 to 20 hours a day across much of the island —  on deteriorating infrastructure, fuel shortages and rising demand.

Storm complicated deliveries of fuel

Strong winds that began with Hurricane Milton last week had also complicated the island's ability to deliver scarce fuel from boats offshore to feed its power plants, officials have said.

Fuel deliveries to the island have dropped off significantly this year, as Venezuela, Russia and Mexico, once key suppliers, have reduced their exports to Cuba.

Key ally Venezuela slashed by half its deliveries of subsidized fuel to Cuba this year, forcing the island to search elsewhere for far more pricey oil on the spot market.

Cuba's government also blames the U.S. trade embargo, as well as sanctions under then-president Donald Trump, for ongoing difficulties in acquiring fuel and spare parts to operate and maintain its oil-fired plants.

The United States on Friday denied any role in the grid collapse in Cuba.