Irma, the most powerful Atlantic hurricane on record, lashed Puerto Rico with flooding rain and powerful winds Wednesday night, plunging hundreds of thousands of residents into darkness and threatening destruction across the economically strained U.S. territory.
The center of Irma, which was spinning off hurricane-force winds for 50 miles around, was about 80 miles northwest of San Juan, the capital, at 12:45 a.m. ET. A hurricane warning remained in effect as "tropical storm force winds and hurricane force wind gusts are expected at least through the overnight hours," the National Hurricane Center said.
Sustained winds of 55 mph with gusts to 70 mph bowed trees, knocked out power and locked tourists in their hotels. While the eyewall, carrying its most destructive winds, didn't make landfall, the National Hurricane Center said that because of the storm's counterclockwise circulation, the island could face hours of punishing wind and pummeling rain up to 20 inches from its north.
Ricardo Ramos, chief executive of the island's electric utility, said about two-thirds of the island's electric customers — more than 1 million — were without power late Wednesday.
"Unfortunately, we are seeing a tremendous amount of rainfall over Puerto Rico, which means that flash flooding is one of our biggest concerns," said Kait Parker, a meteorologist for The Weather Channel.
"I still see a lot of people on the roads," Gov. Ricrado Rosselló said at a news conference. "This system is very dangerous. You should not be on the streets."
President Donald Trump, who declared an emergency in Puerto Rico, spoke with Rosselló on Wednesday "to express his support," the White House said.
Irma, a Category 5 storm, made landfall in the Caribbean early Wednesday, killing at least one person on Barbuda and at least two others on St. Martin and St. Barts, authorities said. Widespread flooding and power failures were reported on those islands and Anguilla.
Anne OBrion, a nurse from Richmond, Virginia, knew the hurricane was coming when she booked her vacation in San Juan, the capital, "but I didn't want to give up my trip for it."
So OBrion was stuck in her hotel as Irma made its way past the island Wednesday night. All of the windows were boarded up as word spread that the island could be without power for as long as a month, she told NBC News by telephone.
OBrion said she had told authorities that she's a nurse and was prepared to pitch in if she's needed.
"One doctor can't take care of all these people," she said. "I'm willing to do what's necessary to help people. That's why I do what I do."
Puerto Ricans left many streets virtually deserted after bottled water, flashlights, batteries and other staples flew off store shelves in recent days. Long lines snaked around gas stations southeast of San Juan. Classes were canceled, and schools were stocked with supplies for refugees.
Federico de Jesus, a political consultant and founder of FDJ Solutions in Washington, D.C., was in Puerto Rico celebrating his birthday with his parents on Wednesday, even though he also knew the hurricane was coming.
Being from Puerto Rico, he's accustomed to the threat. But on Wednesday afternoon, he was huddled with his parents in their eighth-floor San Juan condominium unit listening to the whistling winds and watching the trees bend.
"We are stocked up with food and water, and we put [up] tormentas. That's what they are called in Spanish. They are metal covers for the window," de Jesus said. "We have wireless radio, and there's a power plant in the building, but that's only in the common area. ... We are lucky to have that, most people don't."
Even so, by about 5 p.m. the building had lost power, and de Jesus said most other families had taken shelter at a stadium.
Puerto Rico has been ravaged by an economic crisis for the last decade, and many worry that its crumbling infrastructure cannot withstand ferocious winds and rain. Parts of the island could lose power for months, Ramos said Tuesday.
Irma's 185-mph maximum winds inched toward the strongest on record: the 190-mph pummeling that Hurricane Allen gave the Caribbean, northern Mexico and southern Texas in 1980. Puerto Rico hadn't seen a hurricane of Irma's magnitude since San Felipe in 1928, which killed 2,748 people in Guadeloupe, Puerto Rico and Florida.
And the next targets are lined up — the National Hurricane Center said that while fluctuation was likely, Irma was forecast to remain a category 4 or 5 powerhouse hurricane at least into Friday as it marched through the Turks & Caicos Islands, Bermuda, the Dominican Republic, Haiti, Cuba and, eventually, Florida.
"This thing is expected to maintain its strength," Parker said, and that means that as Irma continues north, as much as 20 inches of rain could swamp the Turks & Caicos and the southeast Bahamas with storm surges up to 20 feet beginning late Thursday.
Irma should still be a Category 4 storm when it makes landfall near Miami sometime Sunday, forecasters said. It is then expected to move north along or very near the East Coast on Sunday night into Monday, with a second landfall projected between Savannah, Georgia, and Myrtle Beach, South Carolina, late Monday or early Tuesday.
Life-threatening storm surge and destructive winds were forecast for coastal areas from southern Florida to South Carolina.
"As of tonight, South Carolina is in its path," Myrtle Beach Mayor John Rhodes said Wednesday night. "Now is the time to act."