Hurricane Fiona grew more powerful Tuesday as it rolled past Puerto Rico and the Dominican Republic after pounding the islands with up to 30 inches of rain, triggering overwhelming flooding, mudslides and destruction.

The storm reached the Turks and Caicos Islands as a Category 3 hurricane, blasting the British territory of about 40,000 people with maximum sustained winds of 115 mph. The government imposed a curfew and urged people to flee flood-prone areas as the archipelago braced for a storm surge of 5 to 8 feet.

About 80% of Puerto Rico remained without power early Tuesday, more than 24 hours after the storm shut down the island’s entire electrical system, though officials said they were making progress restoring parts of it. Water service was cut to more than 837,000 customers – two-thirds of the total on the island, officials said.

Gov. Pedro Pierluisi and power distribution company LUMA Energy both said a “big part” of the island would have electricity back by Wednesday, the newspaper El Nuevo Día reported. Pierluisi allowed for the possibility it might take until the weekend. 

The governor also requested a major disaster declaration, which if granted would free up federal funds for public and individual assistance. U.S. Senate Majority Leader Chuck Schumer said he would urge the federal government to cover 100% of disaster response costs as part of that declaration, instead of the usual 75%.

In the Dominican Republic, more than 1 million people were without running water and 700,000 homes and businesses were without power, the national Emergency Operations Center said.

At least three deaths were reported, two in Puerto Rico and one in the Dominican Republic.

IMAGES:Hurricane Fiona floods homes, streets in Puerto Rico 

HOW TO HELP:A look at mutual aid, nonprofits to help support Puerto Ricans


More rain was forecast through the week in parts of Puerto Rico, and conditions were not expected to significantly improve. “Catastrophic and life-threatening flash, urban, and moderate to major river flooding, as well as mudslides, are likely for southern and eastern Puerto Rico through Tuesday due the rainfall from Hurricane Fiona,” the National Weather Service warned.