Updated at 2:45 a.m. ET Thursday

Hurricane Maria has damaged Puerto Rico's power infrastructure in ways that, in a worst-case scenario, could take months to repair, Gov. Ricardo Rosselló told CNN late Wednesday.

"Our telecommunications system is partially down," he said. "Our energy infrastructure is completely down."

Rosselló said that the island's energy infrastructure is "a little bit old, mishandled and weak," and towers carrying high-voltage lines may have been toppled by the storm. The National Guard will assess the lines from the air once conditions are safer, he said.

The head of Puerto Rico's emergency management agency said such damage would leave the entire island without power.

"When we can get outside, we will find our island destroyed," Abner Gómez of the emergency management agency said at a news conference Wednesday. "The information we received is not encouraging. It's a system that has destroyed everything it has had in its wake."

There had been one death reported so far — a man who was struck by a flying board, Rosselló said.

On Wednesday afternoon, on Twitter, Rosselló ordered a mandatory curfew from 6 p.m. to 6 a.m. until Saturday morning.

Only health care workers, emergency officials, police, journalists and citizens who are dealing with an emergency situation are exempted, he said.

After devastating parts of the Caribbean, Hurricane Maria made landfall in Puerto Rico early Wednesday as a Category 4 storm packing powerful sustained winds of 155 mph, according to the hurricane center.

It is the strongest storm to have hit the U.S. territory in decades.

But as the storm moved offshore, it weakened to a Category 2 hurricane with maximum sustained winds of 110 mph, according to the 11 p.m. advisory issued by the National Hurricane Center. Maria is 55 miles northeast of Punta Cana, Dominican Republic.

In its 2 a.m. advisory, the hurricane center reported that Maria had regained major hurricane status as it neared the Dominican Republic. It is again a Category 3 hurricane. Torrential rain continues to pound Puerto Rico.

"Very high winds are just tearing trees apart," Miguel Santiago with radio station WRTU in San Juan, Puerto Rico, reported Wednesday morning. "Most of the island is without power ... or water."

Maria came ashore at 6:15 a.m. ET near the eastern municipality of Yabucoa. As the eye moved offshore in the afternoon, Maria lost some of its punch and was initially downgraded to a Category 3 storm on the Saffir-Simpson wind scale, with sustained winds near 115 mph.

"[The] core of Hurricane Maria will continue to move away from Puerto Rico during the next several hours, and then pass offshore of the northeastern coast of the Dominican Republic early Thursday, according to the 11 p.m. advisory. "Maria should then move near the Turks and Caicos Islands and the southeastern Bahamas Thursday night and Friday."

The advisory says Maria is moving toward the northwest at about 9 mph "and this general motion with a decrease in forward speed is expected through Thursday night. A turn toward the north-northwest is forecast on Friday."

Widespread flooding was reported across Puerto Rico, according to The Associated Press, in addition to damage from the punishing winds that ripped doors off hinges and sent roofs airborne.

"One of the shelters in San Juan had to relocate refugees to the hallways because of the roof — it was shaking due to the winds," Santiago said.

The last Category 4 hurricane to make landfall in Puerto Rico was in 1932. Two weeks ago, Puerto Rico avoided the worst of Irma, which went on to strike Florida.

In the days before Maria hit the island, Puerto Ricans were urged to heed hurricane warnings and evacuation orders.

"We expect severe devastation," Rosselló told NPR on Tuesday. "We have about 500 shelters. People have been trickling into those shelters. But really, we have some weak infrastructure in terms of some of the homes that we have in Puerto Rico."

By Wednesday morning, more than 11,000 people on the island had gone to shelters to wait out Maria, the governor tweeted.

As the storm hit, Rosselló said on Twitter that "God is with us; we are stronger than any hurricane. Together we're going to get up." He said he has asked President Trump to declare Puerto Rico a disaster zone, which would clear the way to federal aid, according to AP.

Elie Finegold of Dallas was riding out the storm at a San Juan hotel. On Wednesday, he said on Facebook: "The tops of all the palms are gone, many other trees and traffic poles are down, roofs are torn off, and the city remains completely hunkered down waiting for the next round."

Finegold told NPR that he came to the island to be with a friend who had his leg amputated. "Nobody should go through that alone." He said his friend's hospital room "has significant water on the floor and still has no air conditioning (it is hot and humid here)."