(The Hill) — The entire island of Puerto Rico lost power Sunday as Hurricane Fiona hit the U.S. territory with dangerous winds and flash flood conditions. 

The Category 1 storm knocked out Puerto Rico’s power grid when it swept through the southwest coast, affecting the entire island. 

The island has been under a hurricane warning since Saturday, when the National Hurricane Center alerted that Fiona could cause “life-threatening flooding and mudslides” as it ripped along the island’s coast. 

The hurricane warning continued through the weekend and was replaced by a tropical storm warning Monday.  

Early Monday, the eye of the hurricane was on the move past the island, but heavy rainfall, flash flooding and other dangerous tropical storm conditions are still impacting the island as the storm passes by, according to the National Weather Service at San Juan.  

As much as 25 inches of rainfall has accumulated in some areas of the island over the last two days, according to the weather service, and power is still out for most of the island. 

The outages at one point impacted all of the nearly 1.5 million customers tracked on the island by the site PowerOutage.US. Gov. Pedro Pierluisi confirmed in an update Sunday that the island’s full electrical system was down, impacting Puerto Rico’s full 3.2 million population, according to translations. 

LUMA Energy, which services the island, reported Monday that power had been restored for about 100,000 customers. 

LUMA says full power restoration could be days away, as the dangerous conditions are preventing damage assessment and response.

Puerto Rico’s National Guard, its emergency management department and first responders are running rescue missions across the island, according to a Tweet from Pierluisi. 

President Joe Biden on Sunday declared an emergency and authorized the Department of Homeland Security’s Federal Emergency Management Agency to help coordinate disaster relief. 

Fiona comes five years after Hurricane Maria devastated the territory. 

The storm is now approaching the neighboring island of the Dominican Republic.

“The center of Fiona will persist over eastern Dominican Republic into this afternoon… These rainfall amounts will continue to produce life-threatening and catastrophic flooding along with mudslides and landslides across Puerto Rico,” the National Hurricane Center in a new advisory warns.

Similarly dangerous conditions are expected as Fiona moves over the Dominican Republic.