Cuban authorities say at least six people have been killed after Hurricane Oscar made landfall over the weekend, with the government still working to re-establish power after days of blackouts.

In a social media post on Monday, Cuban President Miguel Diaz-Canel said preliminary data showed at least six deaths resulting from the storm, which brought strong winds and rain to the eastern end of the island when it made landfall on Sunday. He said rescue efforts continue in some parts of the island.

“The last thing we want is that, as a consequence of a fallen power line, we suffer another collapse of the system,” said Energy and Mines Minister Vicente de la O Levy, addressing efforts to restore power.

Electricity is slowly returning to Havana, Cuba’s capital, days after a nationwide blackout plunged the country of 10 million into total darkness on Friday, causing the government to close all non-essential workplaces and cancel school classes until Thursday.

According to Cuban officials, power was brought back to almost 90 percent of Havana as of Monday. Other areas remain without power, even after the island’s largest power plant was back online and helped boost generation.

Many Cubans were still holding their breath after earlier announcements that the crisis was over were quickly dashed by renewed power cuts, leaving only hospitals and essential services operational.

“We should not expect that when the system comes back online the blackouts will end,” electricity official Lazaro Guerra said on Monday, cautioning against excessive optimism.

“It’s back!!” Giovanny Fardales, a relieved 51-year-old unemployed translator, wrote in a text message to Al Jazeera on Monday, accompanied by a photo of an illuminated electric lamp on a table by his telephone.

“How long before they cut it again? That’s the question. Not being negative, just realistic,” he added.

Adding to concerns, Hurricane Oscar made landfall in eastern Cuba late Sunday afternoon as a Category 1 storm. A relatively small storm, it quickly weakened as it moved inland, the United States National Hurricane Center said, causing waves up to 4 metres (13 feet) along the eastern coast.

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