SAN JUAN, Puerto Rico – About half of all homes and businesses in Puerto Rico were without power Wednesday as Hurricane Ernesto moved north into the warm waters of the Atlantic after dumping torrential rains on the U.S. territory.

More than 725,000 homes and businesses on the island were without power, out of a total of about 1.5 million customers, according to LUMA Energy, the Caribbean island’s largest electricity provider.

Juan Saca, president and CEO of LUMA, said he could not specify the extent of the damage to the system or how long it would take to restore power. He said more than 1,500 Saca employees were working on the ground.

“We are in the process of restoring service,” Saca said. “We need to assess what needs to be done to resolve the issue.”

Puerto Rico’s power grid is notoriously fragile. In 2022, Hurricane Fiona left about 80% of the island’s homes and businesses without power for a month. Five years earlier, Hurricanes Irma and Maria destroyed the island’s power grid, causing outages in some areas that lasted nearly a year.

Since Fiona, the U.S. Congress has approved $1 billion in funding to modernize and stabilize Puerto Rico’s power grid.

As of Wednesday afternoon, Ernesto, which had strengthened from a tropical storm to a Category 1 hurricane earlier in the day, was located about 365 kilometers northwest of the Puerto Rican capital of San Juan and moving northwest with winds of about 120 kilometers per hour, the National Hurricane Center said.

Ernesto, the fifth named Atlantic storm of the season, is expected to approach the British island territory of Bermuda, about 680 miles (1,093 km) east of North Carolina, by Saturday, and rains are expected to begin as early as Thursday, the NHC said. Ernesto could become a major hurricane in about 48 hours, it said.