A dam failure in Puerto Rico has sent tens of thousands of people fleeing the rushing waters that are threatening downstream communities in the wake of torrential rains unleashed by Hurricane Maria.

Fears had grown overnight and evacuations had begun, but footage showed the dam, located in northwest city of Guajataca, failing and a spillway being overrun with rushing waters:

We just received new video of the dam failure coming out of Lake Guajataca, PR. #PuertoRico pic.twitter.com/LMdXzKEca4 — WeatherNation (@WeatherNation) September 22, 2017

On Friday night, the National Weather Service warned the failure of the dam might be "imminent" and could lead to "life-threatening" flash floods for the estimated 70,000 people living in the immediate area. "This is an EXTREMELY DANGEROUS SITUATION," the NWS wrote. "All the areas around the Guajataca River must evacuate NOW. Your lives are in DANGER."

Speaking to Reuters by phone on Saturday, Christina Villalba, an official for the island’s emergency management agency, said there was little doubt the dam was about to break.

"It could be tonight, it could be tomorrow, it could be in the next few days," Villalba said, "but it's very likely it will be soon."

The Daily Mail reports Saturday how rushing water was "seen sweeping through the municipalities of Isabela and Quebradillas after the dam sustained structural damage" after "nearly 16 inches of rain fell in the area, significantly raising water levels on the 90-year-old dam."

Writing at his Informed Comment blog, historian Juan Cole on Saturday argued that the failure of the dam, related as it is to the extreme weather now exacerbated by global warming and climate change, should serve as a lesson for policy makers and the general public who must hold to account governments that fail to act.

"If you deny climate change, you will not anticipate heavier rainfall. Your dams will then fail, creating tens of thousands of climate refugees," wrote Cole.

As Reuters notes, "The potential calamity was unfolding as Puerto Ricans struggled without electricity to clean up and dig out from the devastation left days earlier by Maria, which has killed at least 25 people across the Caribbean, according to officials and media reports."

Cole concluded, "When you vote for denialist politicians, you are selecting people who make policy. The policy they make will be clueless and will actively endanger the public. Climate change is real. We are causing it by our emissions. If you don’t believe that, you are not a responsible steward of our infrastructure and of our lives."