Puerto Rico was plunged into darkness early Tuesday morning as a power outage spread across most of the island.

The cause of the power outage is under investigation, but preliminary findings point to a fault in an underground line, according to Luma Energy, the island’s main power provider. Full recovery can take between 24 and 48 hours. The company said on X.

According to the New York Times, at about 1000 AST (1400 GMT), only 13 percent of the island’s 1.4 million customers had power.

An hour later, power was restored in some areas and at the San Juan municipal hospital, Luma said.

The New Year’s Eve power outage prompted renewed calls from elected officials and residents to address the unincorporated U.S. territory’s ongoing power problems that have persisted since Hurricane Maria in 2017.

“The island can no longer put up with an energy system that so often fails its citizens,” wrote Jenniffer González-Colon, Puerto Rico’s current U.S. congresswoman and future governor of Puerto Rico, on X.

Power outages continue to impact Puerto Rico’s economy and quality of life, she said.

On Facebook, current governor Pedro Pierluisi demanded answers and solutions from the two largest energy companies, Luma and Genera.

Hundreds of thousands of residents were affected by power outages at the same time this year. A power outage in June left about 350,000 customers without power as temperatures rose, and more than 700,000 customers lost power after Hurricane Ernesto in August.

As they woke up to another day without power, Puerto Ricans expressed their frustration to U.S. media.

“They are part of my everyday life,” Enid Núñez, 49, told the Associated Press about the outages.

Puerto Rico’s power grid was already strained before Hurricane Maria devastated the island. U.S. government funding helped stabilize the electric grid, facilitate recovery projects after other natural disasters, and make other important infrastructure improvements.

However, according to a February 2024 report, implementation was incomplete due to various factors, such as problems starting construction and Federal Emergency Management Agency requirements to authorize the use of some funds report from the US Government Accountability Office.

“Inexcusably, the power grid has still not recovered from the damage caused by Hurricane Maria,” Mark Levine, New York’s Manhattan borough president, wrote on X.

New York City is home to the largest Puerto Rican community in the mainland United States.

“That’s 3.5 million American citizens,” he wrote. “We have much better things to thank them for.”