Power slowly being restored in Puerto Rico after more than 1 million left in dark in New Year's Eve blackout

An island-wide blackout in Puerto Rico Tuesday left more than 1 million residents without power ahead of New Year's Eve celebrations, with crews working for hours throughout the day to get the lights back on.

As of Tuesday night, more than 12 hours after residents woke up without power, still more than half of customers were without electricity, according to power company LUMA.

By 11 p.m. local time, crews had restored power to roughly 700,000 customers, representing about 47.8% of its customers, the power company said in an update on social media platform X.

The power company said both San Juan airports are in service, along with 31 hospitals. Crews also worked to energize key water facilities, the company said.

In an earlier statement, LUMA apologized for the outage.

"We understand the deep frustration that the blackout situation on a day like today is causing to our customers and families across the Country," the statement said. "To all, we apologize for the impact that the event, which continues to be investigated, has had on the plans to bid farewell this year and welcome the New Year."

The exact cause of the power outage, which began at 5:30 a.m. local time, remains under investigation.

Earlier Tuesday evening, the White House issued a statement saying that President Joe Biden had been briefed on the situation.

"Secretary of Energy Jennifer Granholm spoke with the Governor of Puerto Rico and at the President's direction offered to provide any federal assistance that they need to speed power restoration," the statement said.

Biden also spoke on the phone with Gov. Pedro Pierluisi to talk about the power outages and to offer federal support, according to the White House.

Pierluisi earlier said work was underway to restore the service at energy plants in San Juan and Palo Seco.

The U.S. territory has continued to face a slow rebuild of its infrastructure since Hurricane Maria caused widespread damage to the island in 2017.

In 2020, 1 million customers were without power following back-to-back earthquakes. An explosion and subsequent fire at a substation left 900,000 customers on the island without power in June 2021.

Another massive fire at a major power plant caused a massive outage for about 1.3 million customers in April 2022, followed by Hurricane Fiona in September of that year.