(CNN) All people living near the Guajataca River in northwest Puerto Rico should evacuate immediately because of an "imminent dam break," the National Weather Service in San Juan said Friday afternoon. "All Areas surrounding the Guajataca River should evacuate NOW. All Areas surrounding the Guajataca River should evacuate NOW. Many parts of Puerto Rico are flooded and more than 3 million people don't have electricity. 215PM FLASH FLOOD EMERGENCY for A Dam Failure in Isabela Municipality y Quebradillas Municipality in Puerto Rico... #prwx pic.twitter.com/L3utOjxspR — NWS San Juan (@NWSSanJuan) September 22, 2017"It is (done) in the blackness of the night," he said.

Source: CNN September 22, 2017 20:44 UTC