Some 70,000 people have been ordered to evacuate their homes after a rain-swollen dam in Puerto Rico failed in the latest disaster caused by Hurricane Maria.
With the death toll from the storm at 33 across the Caribbean, the National Weather Service office in capital San Juan Friday issued a flash flood warning for people living along the Guajataca River and said the 1920s earthen dam was in danger of collapsing altogether.
"All Areas surrounding the Guajataca River should evacuate NOW. Their lives are in DANGER!," the service said in a tweet. Flooding has already begun downstream, it said.
Shortly thereafter, Governor Ricardo Rossello issued an order for some 70,000 people living in the area in the northwest of the island to get out.
According to the newspaper El Vocero, Public Safety Secretary Hector Pesquera said a drain that normally releases a stream of water from the dam in a controlled fashion had broken.
Instead the busted drain sent water gushing down a ramp-style conduit, eventually washing away huge chunks of soil from the grassy green slope of the dam, according to video on the WeatherNation website.
However the flash flood warning was only due to last until 0600 GMT, the weather service said, suggesting that the river waters were receding.
Puerto Rico was already battling dangerous floods after Hurricane Maria ravaged the island early Wednesday. Rescuers raced against time to reach trapped residents.
Rossello has called Maria the most devastating storm in a century after it destroyed the US territory's electricity and telecommunications infrastructure.
Rossello told CNN the island is lacking communications and the preliminary assessment at this point is 13 fatalities.
"Right now our efforts are to make sure we have everybody safe, that we can rescue people. Our efforts have already produced almost 700 rescues so we're clearly focused on that."
The National Hurricane Center said some areas in Puerto Rico could see 40 inches (more than a meter) of rain from Maria, and Rossello warned of dangerous mudslides brought on by the deluge.
"We have a lot of flooding, we have reports of complete devastation of vulnerable housing. Of course it's still raining over here."
Maria has been blamed for at least 33 deaths, including 15 in Dominica, three in Haiti and two in Guadeloupe.
After lamenting that Puerto Rico had been "absolutely obliterated" by Maria, US President Donald Trump spoke with Governor Rossello Thursday night and promised to speed up relief efforts.
The northern town of Toa Baja was one of the worst devastated areas -- first ravaged by gusts of more than 200 kilometers per hour, then inundated after the island's largest river, La Plata, overflowed.
Many residents did not evacuate on time, while others say they never heard the warning sirens. Some were returning home after several days away, to clear the heavy mud left by the floodwaters from their homes and start the process of rebuilding.
Marisol Rosario, a 55-year-old housewife who had fled with her husband, said she was forced by the winds to leave their dog behind. "I thought I would find him dead, but he managed to climb on top of the furniture and survive," she said tearfully.
The torrential rain had turned some roads into muddy brown rivers, impassable to all but the largest of vehicles.
Toppled trees, street signs and power cables were strewn across roads that were also littered with debris.
Puerto Rico's electricity network has been crippled by the storm and engineers say it could take months for power to be fully restored.
The local electricity board has promised that their priority will be to restore power to hospitals, water treatment plants and pumping stations.
Brock Long, who heads the US federal government's emergency management agency FEMA, said that ships carrying millions of meals and bottled water were trying to dock as the island's ports are slowly reopened.
After devastating Puerto Rico, the storm headed west toward the Dominican Republic where it damaged nearly 5,000 homes and caused more than 18,000 people to evacuate, according to a statement by the office of president Danilo Medina.
As of Friday night, Maria was a Category Three hurricane with winds of 125 miles per hour (205 kilometers per hour), churning in the sea some 365 miles east of the central Bahamas.
Heavy rains and high winds began hitting the archipelago on Thursday afternoon.
The government opened new shelters after several buildings which had been used during Hurricane Irma earlier this month were damaged and authorities feared they might not hold up under another fierce storm.
Maria previously tore through several Caribbean islands, claiming the highest toll on Dominica, which has a population of around 72,000 and has been largely cut off from the outside world.