Maria weakens to Category 2, Puerto Rico dealing with threat of dam failure

— -- Fears in storm-battered Puerto Rico have shifted to a failing dam as the U.S. territory reels from the devastating impact of Hurricane Maria.

Early Saturday morning, the National Weather Service said failure of the Guajataca Dam in northwest Puerto Rico is "imminent" and could cause "life-threatening flash flooding" downstream on the the Guajataca River. Dam operators said it began to show signs of failing, causing flash flooding, on Friday around 2:10 p.m. ET.

"Move to higher ground now," the National Weather Service urged residents in the area. "This is an extremely dangerous and life-threatening situation."

At a press conference Friday afternoon, Puerto Rico Gov. Ricardo Rossello said all available resources were sent to evacuate people near Lake Guajataca, where the dam at the northern end is in danger of breaking. This evening NWS San Juan tweeted that nearly 8,000 people live in the could be affected. Earlier in the day the number given had been an estimated 70,000 people.

Maria weakened to a Category 2 hurricane Sunday, with maximum sustained winds of 110 mph as of 5 a.m. ET. The storm at the time was moving toward the north at 9 mph and its eye was located about 530 miles south-southeast of Cape Hatteras, North Carolina, according to the National Hurricane Center.

The storm is still projected to stay off the East Coast, but tropical storm or hurricane watches could be put in effect for the Carolina or Mid-Atlantic coasts on Sunday with tropical storm-force winds currently extending 240 miles from the eye.

The death toll in storm-hit areas is rising as Hurricane Maria continued to barrel through the Caribbean on Saturday, three days after its landfall in Puerto Rico left the island in the dark.

At least 24 people have died in the storm, including 15 in Dominica, seven in Puerto Rico and two in Guadeloupe.

Maria came ashore in Puerto Rico early Wednesday as a powerful Category 4 hurricane with 155 mph winds -- the first Category 4 to hit the island since 1932. The storm wiped out the island's power grid and dumped 20 to 30 inches of rain in 24 hours, with some areas seeing 40 inches locally.

There is potential for the death toll in Puerto Rico to rise, the island's secretary of the department of safety said Friday.

Although Maria has hurtled past the island, Puerto Rico will see heavy rainfall through Saturday from the storm's trailing rain bands, likely an additional 3 to 6 inches, according to the National Hurricane Center.

Water supplies on the island are lacking because of the lack of power, Rossello said. In addition, the water agency suffered "severe damage," he said.

Rossello has also extended a curfew and ban on alcohol sales on the island from 6 p.m. to 6 a.m. ET through Sunday.

New York Gov. Andrew Cuomo departed for Puerto Rico on Friday to bring donated supplies to the island and assess the need after Puerto Rico's governor made a request for aid. Cuomo traveled with members of the National Guard as well as New York congresswoman and Puerto Rico native Nydia Velázquez.

Residents of Puerto Rico's hard-hit north coast were seen wading through floodwater inside what's left of their homes this week.

Every vulnerable house should be considered "completely or partially destroyed," and every flood-prone area was damaged, Rossello said.

ABC News correspondents observed widespread destruction in the town of Guaynabo, about 10 miles south of San Juan where trees and power lines were downed and storefronts and building facades had crumbled. Neighborhoods in Guaynabo were filled with waist-deep floodwaters and destroyed homes that were apparently not built to any kind of code.

Guaynabo resident Ramon Caldero and his family hunkered down in their kitchen during the storm, which caused part of the ceiling to collapse in his sister's room.

"I was worried," Caldero told ABC News on Thursday. "My sister was screaming."

Christy Caban of Nashville, Tennessee, rode out the storm with her husband and 13-month-old baby in their hotel room just east of San Juan.

"We don't have power, we don't have water," Caban told ABC News on Thursday.

Puerto Rico's emergency management agency said 100 percent of the island had lost power by Wednesday afternoon, noting that anyone with electricity was using a generator. The governor said today that ships are arriving with generators.

Abner Gomez Cortes, executive director of the agency, told ABC News more than 12,000 people are currently in shelters, and hospitals are running on generators. Two hospitals -- one in Caguas and one in Bayamon -- were damaged in the storm.

In a news conference Saturday, Rossello said 9 deaths were blamed on the storm.

Running water has been restored for 20 percent to 25 percent of the island, or about 320,000 customers, and about 25 percent of telecommunications are working, primarily in the San Juan metropolitan area.

Meanwhile, telecommunications throughout the island have "collapsed," Cortes said, describing the storm as unprecedented.

Multiple transmission lines sustained damage, according to Ricardo Ramos, director of the Puerto Rico Electric Power Authority. Ramos said he hopes to start launching helicopters by this weekend to begin inspecting the lines.

The curfew Rossello imposed a curfew on the island Wednesday from 6 p.m. to 6 a.m. ET, which was initially ordered through Saturday, has been extended indefinitely, and the hours changed to 7 p.m. to 5 a.m.

Puerto Rico narrowly missed landfall by Hurricane Irma two weeks ago, with the Category 5 storm traveling just north of the U.S. territory. The island suffered heavy rain and wind, but nothing near the widespread damage incurred by Maria.

Speaking at the United Nations General Assembly in New York City on Thursday, President Donald Trump said Hurricane Maria "absolutely obliterated" the U.S. territory and "totally destroyed" its power grid, but that the recovery process will begin soon with "great gusto."

Puerto Rico "got hit with winds, they say they’ve never seen winds like this anywhere," Trump added.

On the forecast track

Maria passed near Turks and Caicos on Friday. The storm's core is expected to turn toward the north by Saturday night, moving away from the Bahamas and into the open waters of the western Atlantic Ocean, according to the National Hurricane Center.

On Friday, the National Hurricane Center warned a "dangerous storm surge" coupled with "large and destructive waves" will raise water levels by as much as 9 to 12 feet above normal tide levels in parts of Turks and Caicos and the Southeast Bahamas. And through Saturday, Maria was expected to produce up to 20 inches of rain in parts of Dominican Republic and Turks and Caicos.

Though Maria is forecast to gradually weaken next week as the hurricane moves into the cooler waters of the Atlantic Ocean, little change in strength is forecast during the next 48 hours, according to the National Hurricane Center.

The diminishing storm will move between Bermuda and the eastern coast of the United States before likely heading further east and out to sea sometime next week, according to the latest forecast models.

The storm's path is still expected to steer clear of the U.S. mainland.

"At this point, I don’t think Maria will have any major impacts to the mainland besides the high surf and rip currents," ABC News senior meteorologist Max Golembo said Friday.

Ground swells generated by Maria's intense winds are increasing along parts of the southeastern U.S. coast and Bermuda. Ground swells also continue to affect Puerto Rico, the Virgin Islands, the northern coast of Hispaniola, Turks and Caicos and the Bahamas. These swells will likely cause "life-threatening surf and rip current conditions," according to the National Hurricane Center.

Other Caribbean islands devastated

Maria also did severe damage to other Caribbean islands without making landfall.

Dominica's prime minister, Roosevelt Skerrit, told ABS Television on Thursday that at least 15 people have died and many homes are destroyed beyond repair. The death toll in the island nation is likely to rise and search and rescue missions are ongoing. At least 16 additional people are missing in some communities, he said.

“We have many deaths, but it is a miracle that we do not have hundreds of deaths in the country,” Skerrit told ABS Television.

According to Skerrit, the island has no electricity and only limited telecommunications have been restored since the storm. Some villages are now only accessible by sea or via helicopter

The prime minister told ABS Television that his home's roof was ripped off during the storm and he had to take cover under a bed to protect himself from falling debris.

While wiping away tears during the emotional interview, Skerrit issued an urgent appeal for desperately needed aid, namely water, tarps and baby supplies.

“It’s going to take us a very long time to get back,” he said.

Hartley Henry, an adviser to Dominica's prime minister, told reporters via WhatsApp on Wednesday that his country has suffered a "tremendous loss of housing and public buildings" since the storm hit, ripping off roofs and tearing doors from hinges. Dominica's main general hospital "took a beating" and "patient care has been compromised," he said.

"The country is in a daze -- no electricity, no running water," Henry said via a WhatsApp message. "In summary, the island has been devastated."

The Ross University School of Medicine, based in Portsmouth, Dominica, announced Wednesday on Facebook that it is attempting to make contact with all of its students. More than 1,400 students and faculty have signed the registration sheet so far, and the school has reached out to the family members of more than 700 others, who informed them that they are safe.

In Guadeloupe, officials announced Wednesday two people were killed and two others were missing in the storm's wake.

France's Interior Minister Gerard Collomb said some 80,000 people in Guadeloupe -- around 40 percent of the population -- were without electricity Wednesday. Many roads there are impassible due to flooding and French Navy planes have not been able to assess the damage on the island due to bad weather conditions.

In Martinique, about 70,000 homes were without electricity and 50,000 homes did not have access to safe drinking water Wednesday. Fallen trees and downed power poles have blocked many roads there, Collomb said.

Police and soldiers have been deployed in both Martinique and Guadeloupe to ensure security. More than 3,000 first responders are on the French Caribbean islands, according to Collomb.

The U.S. Department of State sent a message of solidarity Wednesday to the people of Dominica and all across the Caribbean who were affected by Maria.

ABC News' Benjamin Gittleson, Max Golembo, Melissa Griffin, Joshua Hoyos, Victor Oquendo and Paul Pradier contributed to this report.