Puerto Rico suffered the latest in a series of widespread power outages on Tuesday that have left 1.3 million customers, about 80% of the entire island, in the dark.

More than a million energy customers have been without power across the U.S. territory since 5:30 a.m. due to an infrastructure problem at a power plant on the island’s southern coast, energy company LUMA said in an update to X.

LUMA said in a statement that the fault appeared to be an underground cable and that it was working with partners to get the island’s power grid back online.

“LUMA will gradually restore power to customers. We have already begun restoring some customers, with the full recovery process expected to take between 24 and 48 hours depending on conditions,” the company said.

Josué Colón, director of the Puerto Rico Electric Power Authority, said in a radio interview that a problem with a power line in the south caused a “cascade effect” that led to the failure of several power plants. He said it would take “a good part of the day” to fix the problem.

Puerto Rican Gov. Pedro Pierluisi said on X that he was in contact with LUMA and the private energy company Genera PR.

“We demand answers and solutions from both LUMA and Genera, which must accelerate the restart of the power generation units outside the fault area and properly inform the population of the measures they are taking to restore operations throughout the island,” he said.

Luis Muñoz Marín International Airport said it was working on power generators but flights were operating normally.

Power outages are frustratingly common for many Puerto Ricans. A series of power outages over the summer sparked protests and led San Juan Mayor Miguel Romero to declare a state of emergency.

These protests led to the US-based Genera PR taking over the management of formerly state-owned power plants that are on average 45 years old – twice as old as equivalent plants in the US mainland – and rely heavily on fossil fuels.

More than 700,000 customers were without power in Puerto Rico in August when Tropical Storm Ernesto hit the island.