HAVANA, Cuba (AP) — An island-wide blackout hit Cuba on Monday as fuel reserves dwindle and its electric grid continues to crumble.

The blackout in the country of 10 million people was reported by the state-run Electric Union, which said on X that the cause is under investigation. The Ministry of Energy and Mines wrote on X that it has activated protocols to restore electricity.

Fuel has been running out across Cuba since January, when U.S. President Donald Trump threatened tariffs on any country that sells or provides oil to the island, deepening the island’s ongoing economic and financial crisis. Public transportation has largely been halted, and officials have canceled tens of thousands of surgeries.

Cuba produces only 40% of the fuel it needs, while the 730,000 barrels of oil delivered by a Russian tanker in late March ran out by the end of April.

The government also has been rationing power with intentional outages that can stretch to more than 24 consecutive hours.

A blackout in mid-May affected the island’s eastern provinces, while a blackout in mid-March struck the entire island.