Resident, Tito Alman, told Reuters no one expected this much devastation on an island used to hurricanes.
The Category 1 hurricane will likely become a Category 3 as it moves across warm Caribbean waters toward the Turks and Caicos.
After strafing Puerto Rico, Fiona made landfall in the Dominican Republic near Boca Yuma at 3:30 a.m. local time, according to the NHC. The centre of the storm had reached the northern coast of Hispanola before noon.
In Puerto Rico, a territory of the United States, residents were still facing strong winds, frequent lightning and heavy rain.
Fiona made landfall there on Sunday afternoon, dumping up to 30 inches (76.2 cm) of rain in some areas.
The storm comes five years after the U.S. Caribbean territory was ravaged by Hurricane Maria, which triggered the worst U.S. power blackout.
Nearly 90% of Puerto Rico remained without power on Monday, according to Poweroutage.us. Officials said it would take days to reconnect the whole island of 3.3 million people.