SAN JUAN, Puerto Rico (AP) — A power outage struck most of Puerto Rico early Tuesday as the U.S. territory prepared to celebrate New Year’s Eve, leaving more than 1.3 million customers in the dark. Officials said it could take up to two days to restore power.

The outage occurred at dawn, plunging the island into an eerie silence as electrical appliances and air conditioning shut down before those who could afford generators turned them on.

“It had to be December 31st!” shouted a man who gave his name only as Manuel as he stood outside a grocery store in the capital, San Juan, grumbling about the outage, which coincided with his birthday. “There is no such thing as happiness.”

According to Luma Energy, a private company that oversees electricity transmission and distribution, nearly 90% of the 1.47 million customers across Puerto Rico remained in the dark.

Luma said in a statement that the outage appeared to have been caused by the failure of an underground power line and said power would be restored “in the fastest and safest possible manner.” A Luma spokesman told the Associated Press that the incident was under investigation.

The blackout fueled simmering anger against Luma and Genera PR, which oversees electricity production in Puerto Rico, as more people call for their ouster.

Gov.-elect Jenniffer González Colón, who is scheduled to be sworn in on Jan. 2, has called for the creation of an “energy czar” to review possible contract violations by Luma while another operator is found.

“We cannot continue to rely on an energy system that is failing our people,” she wrote on X, adding that stabilizing Puerto Rico’s energy grid would be her top priority in office.

Meanwhile, Governor Pedro Pierluisi said he was in contact with Luma and Genera PR, adding on X that “we demand answers and solutions.”

The outage forced businesses, parks and several malls to close, and the government announced reduced hours for some of its agencies. Workers examined hundreds of bedridden patients.

Other Puerto Ricans began planning ahead.

“I’m going to my balcony. I’ll sleep there,” Raúl Pacheco said, shrugging, as the 63-year-old diabetic sat on a walker and tended to an injured foot.

Julio Córdova, a city worker, said he got dressed by the light of his cellphone and planned to buy candles.

“It touches me because I had plans. “It couldn’t have been yesterday or tomorrow?” he said, shaking his head as he raked leaves.

While power outages are rare in Puerto Rico, the island struggles with chronic power outages stemming from a crumbling power grid that was leveled in September 2017 by Hurricane Maria, a Category 4 storm.

However, the system was already in decline after years of lack of maintenance and investment.

Most recently, crews began making permanent repairs to Puerto Rico’s power grid following Hurricane Maria. To stabilize the grid, the island continues to rely on generators provided by the U.S. Federal Emergency Management Agency.

In November, Puerto Rico’s government asked U.S. officials for permission to continue using more than a dozen portable generators for two more years.

Some Puerto Ricans took the latest failure in stride.

“They are part of my everyday life,” said Enid Núñez, 49, who said she ate breakfast before work thanks to a small gas stove she bought for such events.

Meanwhile, Puerto Rico’s Electricity Authority, the island’s largest government agency, is struggling to restructure more than $9 billion in debt.

Petroleum-based power plants generate more than 60% of Puerto Rico’s energy, followed by natural gas and coal. On an island with a poverty rate of over 40%, rooftop solar only accounts for about 7% of electricity consumption.