Puerto Rico's governor met mayors from around the ravaged island on Saturday after surveying damage to an earthen dam in the northwestern part of the U.S. territory that was threatening to collapse from flooding in the aftermath of Hurricane Maria.
Some 70,000 people who live downstream from the compromised dam, which has formed a lake on the rain-swollen Guajataca River, were under orders to evacuate, with the structure in danger of bursting at any time.
"We saw directly the damage to the Guajataca dam," Governor Ricardo Rossello said in a Spanish-language Twitter message on Saturday while reinforcing his request that people leave the area as soon as possible.
"The fissure has become a significant rupture," Rossello said separately at a news conference on Saturday.
The U.S. National Weather Service said on its website the dam was still in danger of failing and triggering life-threatening flash floods.
"Stay away or be swept away," it warned.
Meanwhile, people across the island were struggling to dig out from the devastation left by the storm, which killed at least 25 people, including at least 10 in Puerto Rico, as it churned across the Caribbean, according to officials and media reports.