Cuba’s energy grid collapsed late Sunday, the state-owned electricity utility announced on social media, plunging the Caribbean country into its sixth nationwide blackout this year.

Sunday’s blackout is the first of August and comes as the US continues imposing a blockade of oil that Cuba uses to power its aging energy infrastructure.

The state utility company did not offer further details about the blackout. Efforts to restore the power grid continued on Monday afternoon, state media said.

Cuba has been facing a years-long energy crisis that worsened after the US captured Havana’s closest ally, Venezuelan President Nicolás Maduro, in January and forced the acting government to stop shipping oil to the island. Mexico has also halted exports in response to US pressure.

The island of roughly 10 million people suffered two outages in March and three in July.