(CNN) -- Hurricane Maria was battering the Dominican Republic on Thursday as the long-term devastation in Puerto Rico was just coming into focus.
The Category 3 storm whipped 115-mph winds as it left torrential rain in the Dominican Republic, the National Hurricane Center said.
Maria will likely strengthen over warm water as it headed toward the Turks and Caicos, endangering low-lying islands with enormous storm surges.
But Maria's wrath was far from ended in Puerto Rico. Dozens of families were rescued from flooding Thursday morning in Levittown, near the capital city of San Juan, a spokeswoman for the Puerto Rican governor tweeted.
The Puerto Rican National Guard was still searching for others in need of rescue, she said.
But the task was hampered by a power outage that covered the entire island of 3.4 million people -- with officials saying it may be several months before Puerto Ricans get electricity back.
Here's a look at the islands pummeled by Hurricane Maria:
Dominican Republic braces for flooding
The Dominican Republic couldn't handle much more rain, with rivers still swollen and the ground still saturated from Hurricane Irma.
But the island of 10.7 million people was getting deluged again. Maria could dump 16 inches of rain on the northern and eastern parts of the island, the hurricane center said. The Turks and Caicos could face the same fate.
"Rainfall on these islands will continue to cause life-threatening flash floods and mudslides," the hurricane center said.
Airports on the Dominican Republic had shut down for the storm but were expected reopen at noon ET on Thursday.
Puerto Rico: Power system 'basically ... destroyed'
Puerto Ricans, still grappling with intense rain Thursday, might not get power back for four to six months, said Ricardo Ramos, the CEO of Puerto Rico Electric Power Authority.
"The system has been basically destroyed," Ramos told CNN.
Puerto Rico Gov. Ricardo Rosselló said Maria is the "most devastating storm to hit the island this century, if not in modern history."
The US territory has been through a long recession, is deeply in debt and has a state-owned power grid that is "a little bit old, mishandled and weak," the governor said.
Retired Army veteran Manuel Torres called Maria's devastation the worst he'd ever seen. His mother's house in La Perla, an oceanfront community in old San Juan, was destroyed.
Emerging after the storm had passed, Torres found the three-story home reduced to two stories -- and without a roof.
Angela Magaña, a UFC fighter who lives in the area, said neighbors were helping each other.
"We need cleanup, water, food, and generators," she told CNN. "There are a lot of old people here who are going without necessities. We need to rebuild and restructure, and we need prayers. Any kind of help we can get because it's a mess right now."
While the winds subsided as the hurricane pushed to the northwest, downpours continued in mountainous areas, meaning water would continue gushing downstream, exacerbating flooding.
On Thursday morning, the island was "completely under a Flash Flood Warning. If possible, move to higher ground NOW," the National Weather Service in San Juan warned.
"Catastrophic flash flooding continues," the agency tweeted.
The island's airports were expected to be closed until at least Friday, pending inspection.
Dominica: 'The need is great'
The hurricane killed at least 14 people on the island of Dominica, and those who were spared have "gone into survival mode," Charles Jong, a spokesman for Dominica Prime Minister's office, said late Wednesday.
Desperation for food, water and medical supplies was rampant among Dominica's 73,000 residents.
"The need is great," said Philmore Mullin, head of Antigua and Barbuda's National Office of Disaster Services. "Damage is severe and widespread. We know of casualties, but not in detail. We've heard of many missing, but we just don't know much at the moment."
Looting had become widespread on the island, Jong said, adding that he'd exhausted his own food and water supplies.
Jong said he'd been through "Hurricanes Hugo, Gilbert, Lenny and many others in St. Kitts, but being in Dominica for Maria was the most horrifying experience."
Dominica's Prime Minister, Roosevelt Skerrit, is "homeless" and "bunking up in an area called St. Aroment," Jong said, adding that Skerrit might move into the State House, where the President lives.
A flight Wednesday over the island nation revealed that the storm showed no mercy. Thousands of trees had snapped and were strewn across the landscape, leaving the island stripped of vegetation.
CNN also saw evidence of dozens of landslides, although not in population centers. The usually blue-green sea in many places had been replaced by a muddy brown.
Virgin Islands: Homes left in ruins
Maria also annihilated homes on the US Virgin Island of St. Croix. Aaliyah Bisamber shot video of what was left of her old house on the island of 50,000 people.
Maria didn't just obliterate homes, it knocked out vital communication lines, resident Murillo Melo said.
"Here on the island and on the mainland, people are trying to get in contact with friends and relatives," he said. "People are desperate to get some news from their friends and relatives."
On St. Thomas, retired New York police detective Austin Fields said his home was pummeled.
"My home is no longer a home," he said.
US President Donald Trump declared the US Virgin Islands a major disaster area and ordered federal aid to supplement recovery efforts.
Virgin Group founder Richard Branson, who rode out Hurricane Irma in his wine cellar on his private island in the British Virgin Islands, told CNN after Maria that "climate change is real."
"Look, you can never be 100% sure about links," Branson said. "But scientists have said the storms are going to get more and more and more intense and more and more often. We've had four storms within a month, all far greater than that have ever, ever, ever happened in history."
"Sadly," he said, "I think this is the start of things to come."
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