Officials in Puerto Rico said more than 800,000 people– two-thirds of the homes and businesses – were without drinking water service due to Hurricane Fiona, which has overwhelmed Puerto Rico with flooding and mudslides.

Iran PressAmerica: Hurricane Fiona smashed through Puerto Rico on Monday with pounding rain and winds that triggered mudslides, "catastrophic" flooding and a power outage that swept across the entire island. Hundreds of thousands lacked running water.

More than 1,000 water rescues were performed and more were underway, Gov. Pedro Pierluisi said. Even as the storm made landfall Monday in the Dominican Republic, it continued to slam Puerto Rico with unrelenting rains -- more than 30 inches in southern parts of the island, USA Today reported.

The National Weather Service in San Juan urged residents to move to higher ground "immediately."

"Heavy rainfall and catastrophic flooding continues across much of Puerto Rico," said Richard Pasch, a specialist with the National Hurricane Center.

Authorities reported two deaths in Puerto Rico – one a 58-year-old man swept away by a flooded river in the inland town of Comerio and another one a 70-year-old man burned while trying to operate a generator. Another death was reported in the Dominican Republic, where a person was hit by a falling tree. 

The Aqueduct and Sewer Authority said more than 800,000 customers – two-thirds of the homes and businesses – were without drinking water service. The entire power grid across the U.S. territory went down Sunday afternoon before the storm made landfall, leaving everyone without electricity.

Less than 10% had regained power Monday, and power distribution company LUMA Energy warned that it could take several days to fully restore electricity because of the outage's magnitude.

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